H.,
Is he breastfed or formula fed? Either way, have you talked to your pediatrician about food intolerances or reflux? My oldest son was like that. He NEVER slept. He was up 3 times a night, every night until he was 2. He slept through the night for the very first time about a month before his second birthday. Even now, he sleeps through the night only about half the time (he was up twice last night, yawn!) Some kids are not natural sleepers and it can make life really, really hard for mommy. So now I also have a 5 month old baby who has really severe food intolerances (I breastfeed) and reflux. He's intolerant to dairy, soy, eggs, caffeine, and chocolate. It took about a month after I started my elimination diet to see a big improvement but now he's a happy, smiley, interactive baby who actually sleeps. For a while there, we had a very screamy, miserable, non sleeping baby on our hands. Now that I look back to what we went through with my 3 year old, I realize that he most likely had the same issues although now quite as intensely as his younger brother - which is why it was never really "bad" enough to get a diagnosis. But now that I know what to look for, I realize he likely had issues too....
Even if you are formula feeding, formulas are built from dairy or soy and corn (corn syrup). And many, many babies are intolerant to dairy or soy or corn. There are hypoallergenic formulas but they have different levels of hypoallergenic-ness. They sell some in the grocery store but there is one that I think you can only get via prescription (neocate) that is even more hypoallergenic than what you can buy off the shelf. I haven't gone the formula route so I'm not all that familiar with them, but it could be worth a try to see if it helps. Keep in mind that if you are breastfeeding and you eliminate dairy and soy (most kids who react to one will react to the other because the proteins are really similar), you have to eliminate "hidden" dairy and soy in food (which means reading labels carefully) and once you are dairy and soy free, it can take up to a month for all of the dairy and soy to clear out of your system, although in my experience you will start to see improvement in about a week. I would think if you are feeding formula, it would take a similar amount of time to see if changing formulas would help. Since your son is 8 months old, I'd assume he's eating solid foods, you are also going to have to read the labels on everything he's eating. Even many of the baby cereals has soy in them. FWIW, you are looking to avoid soy PROTEIN. Soy lecthin and soybean oil are fine. If you try to eliminate those, there will be nothing left to eat. LOL It certainly wouldn't hurt to do a little research on food intolerances. In my experience, regular pediatricians know very, very little about food intolerance and give out really poor to dangerous advice in this area. If you think it is a problem, ask for a referral to a pediatric GI doctor.
My other thought will probably terrify you so I'll apologize in advance. My 3 year old non-sleeping child has also turned out to be autistic and he's got some pretty serious sensory issues. I'm not saying your kid is autistic because he doesn't sleep but I'm telling you my experience so if there is an issue, hopefully you will figure it out much earlier than I did. I really do think some of my son's problems were due to food intolerances but it is hard to say which ones were food related, which ones were autism related and which ones were both. It is really, really common for autistic kids to be notoriously poor sleepers. Again, looking back it is always easier to say "well, this must have been caused by X" but at the time, I thought he was just a high needs kid and now I know he was definitely high needs but the reason was autism. So I would recommend that if your son is not hitting his developmental milestones or is hitting them kind of late (my son hit them all at the very end of the "normal" range but still within the normal range), it wouldn't hurt to talk to your pediatrician and get a referral to a developmental pediatrican. This is another area where a regular pediatrician doesn't know much and can give some really bad info (mine swore there was NOTHING wrong with my son until he was close to 3 when we knew there was clearly something not quite right) but you should have a local early intervention office and you can self refer and just make an appointment and it is a free service. If nothing else, they may be able to reassure you that your son is developmentally on track and you can cross that off your list of things to worry about.
I hope you find something in my story that is helpful to you. But in the meantime, I sympathize. Especially now that I have a baby too, I really can't remember the last time I slept for more than about 3 hours in a row. LOL I hate to tell you that you will eventually get used to it, but you really will. Or you may get lucky and not have to get used to it. One thing that really helps me cope is to go to bed earlier. If I go to bed around 9 and know I have to be up around 7 (but typically my 3 y.o. gets up between 4 & 6 a.m. depending on the day but occasionally he will actually sleep later), it is easier to fit in enough sleep to survive if I start with about 9-10 hours to do it. That way even if I'm up a few times, I still get enough sleep that I don't completely feel like dying the next day. If you have the ability to nap during the day, do it and don't feel bad about it. Everything else in your life will feel ten times harder if you are too exhausted to cope so you've got to make sleeping a priority at least some of the time. I know that if I stay up late and have to get up 2-3 times at night, it is really, really tough.
FWIW, I'm not a big fan of letting babies cry it out to learn to sooth themselves but I did try it a few times out of desperation with my son. In my experience, all it did was make him hysterical and then he'd throw up. It then took an act of God to get him to go to sleep. And then he'd wake up screaming at the top of his lungs multiple times for several days afterwards. So, I would really recommend against trying to let him cry himself to sleep. It doesn't work for every kid and for my son, it was terrifying for him.
As far as keeping a baby up all day, with both of my kids, the more tired they are, the worse they sleep. Regular naps and regular bedtimes help both of them sleep more and sleep longer. As far as the teething tablets, if your babe has an issue with dairy, the teething tablets could be making it worse. They have a "milk sugar base" which is dairy. I tried a bunch of the homeopathic stuff with my younger son when all of his problems started but the only thing that really helped was figuring out what in my diet was bugging him and eliminating it. Gripe water helped somewhat but really, treating his stomach ache didn't help nearly as much as eliminating what was causing the stomach ache.
Hoping you find something that helps,
T.