Hi T B
I know you must be so tired. I guess your first boy was a "perfect sleeper", because your 4 month old sounds normal to me :O) Waking up 4-5 times a night was normal for BOTH of my boys. And.....They always ate like I had never fed them before! Actually, my boys slept similar to your newborn also.....
In my opinion, cryng it out is not for a 4 month old. I believe their cries are "real", because they really need something. In your case, your son 4m old needs to suck :o) The best part is he is NOT hungry, so he will eventually be able to soothe himself back to sleep. Maybe he needs a different pacifier with a different "shaped" nipple. Perhaps he's sucking so hard that it falls out of his mouth. He keeps waking up, because he can't soothe himself completely back to sleep yet...so, it's easy for him to wake up.
You can try to rock him at 3:30am to help him sleep deeper the rest of the night. I didn't......I just pulled my son into bed with me to get better rest :O)
At 4 mths old, I thought my 1st son was nocturnal, because he was more restful during the day, than at night. So, his naps were NEVER in peace and quiet....I had to vacuum around him and everything to try to "interrupt his sleep" so he would sleep sounder during the night....do you think your newborn could be like that? Well....this is why I began rocking my son.....to get him to sleep sounder during the night. Plus, it was beautiful....addicting, but very sweet :O) My 13 yr old... to this day....is like clockwork! He is sound asleep before 9pm and POPS up super early around 6am. So, the rocking didn't effect him at all. Or did it?
NOW... my 7 yr old is another story. I didn't rock him, because I was trying to make it "eaiser" on me the 2nd time around :O) Well, he slept sound all by himself for the first 3 years :O) Then he couldn't do it anymore....and tried to keep crawling in bed with me...at 7, we still struggle with this. So, go figure....each kid is different.
Your precious boy is only 4 m's old and has specific needs right now. The need to be fed, changed, held and the need to suck :O) That's about it....You can never love a 4 month old too much (in my opinion)....This is probably the "easiest" age because their needs are so few.
As difficult as it is to see beyond the fatigue.... try to instead, think of his simple needs.....needs that can be satisfied in minutes if it's the RIGHT need :O)
Good luck, T B. I hope can get some more rest soon.
~N. :O)