Hi Mares, Sounds like you have what they call the "Happy Perger". There has been a constant post under new born then sleep and settling. It is the 3rd down from the top its about sleeping with gastric reflux. There is a lot of really good advise there for reflux in general. My son has reflux he is now 14 months old and even had a vomit this morning. A friend of ours has a little girl who is 2 and she still vomits. We found a visit to the chiropractor was the best thing for us. But it is a personal choice. My son even had trouble trying to keep water down. We are lucky in the fact my son can keep his food down. We had the odd accident but not regularly. I did read in the book Baby Love that putting a reflux baby on food earlier than the 4 months would only mean different colour vomits. We didnt find this but perhaps you are going too. The only thing I can think to try, if you not already, would be to be sure to feed your son when its very calm. I would try to sit him up right in his chair and try to leave him there for a short while to give the food some time to settle. Remembering that reflux babies can not be bounced, shaken or ruff handled especially after a feed. My son used to loved being thrown in the air and being caught but we had to be sure he was due for a feed before we would attempt it. My husband would always ask when he come home from work when our son was last fed so he could work out which was the best play for them. If you are going out or he is going to be playing try to feed him a good half an hour prior to activity. You can not rush them or feed them in a hurry or they will vomit all over you on the way to the car. I had to dress or change my son before any feeds or he would bring up on the change table. On the change table we use a pillow which we put him on from his shoulder blades up to his head. Reflux babies as you know have difficulties lying flat. I had to be careful when carrying him as if I had him on my hip and he was slipping off just the jerking movement of lifting him back up on to my hip could be enough to make him vomit.
My son didnt have any problems lying on his stomach but we had to watch the amount of time and of course not after feeds. He slept on his stomach for months due to neck problems. The chiropractor fixed this for him.
I hope things settle for you soon, reflux babies are a world to their own. Good luck!