Sleepless in Las Vegas

For the past two nights, my poor baby has been fighting in the middle of the night what I can only assume is really bad gas. He flails his little arms, kicks out and bends his legs, grunts like a gladiator, and eventually starts to whine a little, all in the middle of a sound sleep, to the point that he wakes himself up, a couple of times a night. And I wake up each time and feel just horrible, because it seems like he is in such discomfort. The other night, after I put him back to sleep, I stayed up, at 4 am, and researched this on the net, and there were others who have experienced the same thing as me. But the explanations varied from it's the babies working things out in their sleep to it's gas and I need to burp better (possibly) to it's acid reflux and the baby needs medicine. So, I am not completely sure what is going on, but I hate it and I feel responsible. Maybe it's something in my diet that he gets in my breast milk. Maybe it's because I nurse him at night lying down and then we both fall asleep and he doesn't get the burping he needs in the middle of the night (although my pediatrician said falling asleep is fine and they don't always burp). I'm not the best burper, and my baby is a pretty gassy fellow, regardless of whether he burps or not. He passes gas through out the day. Maybe it's the formula - I recently switched to a sensitive, lactose-free formula to try to reduce his grunting and straining throughout the day, but perhaps I should switch back. I don't know what it is. Maybe it is acid reflux and lying flat irritates him - although I have noticed that he doesn't sleep as long in his swing anymore either. The place he sleeps the longest is in my arms - four hours last night! Between the worrying and the lack of sleep, I'm a bit exhausted.