Hi J.,
My 3-month-old daughter is the same way. She has been taking Axid for acid reflux since she was 5 weeks old. The things that have really helped me are:
- holding her upright after feeding for 10-15 minutes (which I know is a challenge with another little one running around! I've got an 18-month-old.)
- having her sleep on an incline, such as her carseat, swing, or bouncy seat. She was so cranky after sleeping on her back and has been a different child since we stopped doing that.
- watching "Happiest Baby on the Block" DVD -- the soothing tips, especially the super-tight swaddling, have been lifesavers.
- lots of Mylicon
- the medication for acid reflux -- she's been like a different child since she started it.
I would tell your doctor about his behavior, and see if medication might be appropriate.
If stomach sleeping works, go for it. Like someone else said, taking care of yourself, especially sleeping, is so important. I was very depressed when my daughter was so colicy, and since I've gotten her on medication, and had a post-partum doula come watch the kids once a week, things have improved so much.
Hang in there -- it will get better!