Ok, first I'm wondering why you introduced solids before 6 months. Many studies have shown babies really can't handle solids before 6 months.... and oatmeal is sort of heavy to start. I would have started with rice cereal and then moved on to Oatmeal. So, that could be causing some tummy troubles.
Ok, sore nipples... Medela Pure Lanolin ... awesome. Also, you can go to www.earthmamaangelbaby.com and get some of their nipple cream. It is all natural and works great as well. A little pricey...but worth it.
The pulling off sounds more like baby is frustrated. Question, did you have an overabundance in the beginning? Were you engorged alot? If so, then by now, your body has adjusted to what baby is taking and now she has to work a little harder to get it. That makes her frustrated. I went through this with my daughter about the same time. For the first 4 months or so I had enough milk to feed a third world country and it would let down almost immediately. We had many many issues those first 4 months, included sore, cracked and bleeding nipples. So, I KNOW the pain you are talking about. It is excruciating! I cried through just about every nursing session for 3 months. Seriously.
Keep at it. Pay very close attention, if you feel like she is going to pull away, then take your finger slip it into her mouth and remove her before she has the chance. In addition, if you can leave some milk on your nipple and let it air dry for just a couple of minutes afte rshe nurses, it will help tremendously. Breastmilk has amazing healing properties!!! Truly! And, just so you know, about 2 'good' days and your nipples will feel SO MUCH BETTER!!! It doesn't take long.
Now, if you feel like baby just won't be patient enough to get to let down, then you can do a couple of things. First, try to on off thing to see if you can encourage her to just nurse through it. If that just isn't working, you can try pumping a little so that let down occurs faster. The other thing you can do is massage your breast while baby is nursing. That will increase the flow and baby will be getting the copius amount of milk she is seeking.
Keep in mind, around 5 months they go through a growth spurt. So, she may be demanding more.
The distractions... yes, that is something else entirely. My daughter was HIGHLY distracted. Oh my goodness. I couldn't even nurse in public because she would be so distracted she just wouldn't eat. Everything else was SO much more interesting. Their eyesight at this age is really starting to come into focus. So, literally a whole new world just opened up to them. They can see beyond 12 inches in front of their face. In addition, their hearing is opening up as well. So, lots of new sights and sounds and WOW! So exciting!!! Look mom! Did you see that!! ;-)
What I had to do was make sure all noises were shut off... no radio, no TV, windows closed, curtains drawn to get it a little darker. That helped a lot. The more distractions you can control, the better the nursing session will go.
This phase lasted about 1-2 months for us. After that she was used to the noises and sights and nursed like a champ. Keep in mind, if the sessions are short...that's ok. She may just ask for more of them during the day. Baby WILL eat when she is hungry. (barring any medical conditions that would cause her to not eat, but really I don't think the reflux is an issue here. My daughter had a bit of it too.) Baby is a basic needs person. She will eat when she is hungry, she will sleep when she is tired, etc...
Just relax. If baby isn't following her 'normal schedule'....that's ok. They change it up from time to time. Growth spurts, emerging skills, new sights and sounds ... all of that can disrupt baby's schedule and throw things off. We can't try to conform them to a rigid schedule. General schedules yes...but trying to keep them doing what they always did will just frustrate you both. Things change as the situations and contributing factors change.
It really sounds like everything is completely normal. You just have a couple of issues to work through... and you will.
I have found www.kellymom.com a very useful site.
Good luck and happy nursing!!!!