Sleeping... Ugh

My son who is going to be 5 months old has gone from waking up 1 time at night to 4 times at night.. This has been going on for over 4 weeks.. Regardless of how much I feed him or what time I put him down he will still wake up 4 times at night.. Not always to eat but I think he rolls to his tummy and wakes himself up then cries.. I haven't slept in weeks and on top of getting up to start my day at 4;30am and working tons of overtime I am exhausted.. I have 3 questions At this point do you think he is waking up out of habit and crying? As I mentioned he shouldn't be hungry since I just feed him before hand Would it be bad to put a little tiny blanket with a monkey on it, about the size of a wash cloth in his crib? Thinking tht may comfort him but worried about SIDS Has anyone else gone through this? What did you do to make it better? Did you sleep train? Please any advice would help I'm at a total loss.. It sure if its habit.. If its his constant rolling.. Or if he is scared or wants to just be comforted Thanks