I agree on a couple of points from others' responses.
1. Your doctor should listen and do more.
2. Perhaps you should look to natural methods.
3. If he has constipation issues or hard stools, obviously his digestive/elimination isn't working correctly.
Possible helps would be digestive enzymes (available in fresh fruits and vegetables, and possibly for babies in another form). Also, if he's been on antibiotics, you may consider probiotics for him. Most adults that I work with (I work in the natural health field) who have come in with acid reflux, once they add those two things (enzymes and probiotics), notice amazing results.
Also, being a reflexologist, I would work on his little feet and massage them in the arch area of his foot (you can find a chart), as well as the esophageal area - doesn't need to be hard, just often for him. I would also massage his tummy area (going in a clockwise direction). That could get things 'flowing' better.
Hope things get better,
B. C., CR, SCCI, BCRS, LSH, EFT-CC
Certified Baby Massage Instructor
Board Certified Raindrop Specialist
Natural Health Coach