One of our 10 week old twins has reflux. Regarding medications, please keep in mind that Zantac and Prevacid only help with the burning, the don't stop the reflux itself. In our case, the regurgitation is more the problem than the burning. I agree with a previous poster that it is more important to burp them than to let them sleep. If we burp him, he'll wake up (often loudly), but will sleep better when he finally gets to sleep. Without burping, he will wake up not just once, but hourly as the gasses get into his system. He'll wake up from gas and either need to burp or have flatulence before he can go back to sleep. On advice from our pediatrician, we make sure that he is burped and kept with his head above his stomach for at least 20 minutes after eating. It's helped a lot.
Some solutions: If your mattress is harder, then consider getting some sort of wedge. We have a healthy back wedge (10") like this one:
http://www.healthyback.com/products/Healthyback/Healthy-back-bed-wedge/108 that we cover with large beach towels safety pinned on that works pretty well. We put his behind and legs on the crib mattress and the back and head on the wedge. He does occasionally roll off, but it happens less often than he would wake up from reflux. For a softer mattress, like the one we have in our PnP, we put a boppy pillow under one end and the mattress naturally folds when the baby's weight is on it so that again, he is on the incline from the waist up and flat from the waist down. This position helps keep him from rolling off.
He does occasionally sleep in the bouncy seat and after burping sometimes the bouncy seat with the vibration on will help soothe him to sleep. Last, we also have an reclined position swing (the FP Aquarium Cradle Swing). Sometimes the motion and the reclined position help him sleep.
And unfortunately, sometimes nothing seems to work, but we have the worst results when he hasn't been properly burped. That's the key to improvement (at least for us). Good luck!