I will echo everyone else - the cereal is not working, and is causing MORE issues (choking, not breathing), so stop it. I can't believe he suggested that, and especially that thick! My daughter was on Zantac at first, but it didn't help, and she hated it cause it has a STRONG mint flavor...we switched to the Prevacid solutab - cut it in half with a pill cutter and then rubbed the half on the inside of her cheek with our finger till it dissolved, when she was about 2 months. Worked MUCH better. I still exclusively breastfed, and we just trie to keep her upright all the time, and fed her small amounts every 1.5 to 2 hours.
We also bought a Tucker Sling for her to sleep on/in - that made a HUGE difference in her sleeping. http://www.tuckersling.com/
After more research on my own, I found I had a problem as well as her having reflux...I had a milk imbalance/oversupply, she was getting too much foremilk, and not enough of the fatty hindmilk - all the lactose was hitting her intestines at aonce, and with no fat to slow the digestion/fermentation of the sugars, she was getting VERY GASSY - her poops turned for the typical breastfed yellow and seedy, to bright green and stringy /mucousy like seaweed!!! It was so bad, she even tried to refuse the breast for about a week...she would only nurse in her sleep - awake she would scream and push me away! I figured this out by searching the web, the Dr. had no clue, and I solved it by not switching sides/breasts in the middle of feeding - in fact for a couple weeks, I had to nurse only on one side for 2 feedings in a row, and then do the other side 2 feeds in a row....it sloved the baby's gas issues almost immediately, like after half a day poop was back to normal, took 2 weeks to get my supply to decrease enough to go back to one breast per feeding, and we never got to the point where I hadto/could have her eat both sides in one feeding, and I nursed till she was 9 months.
She was always small, and still is, almost 2.5 years old, and only 24 lbs. and 35 inches...10th and 25th percentile. Out Ped we had at th ebeginning never told me percentiles, I think not to scare me, bacause although small, her development was consistent, she was on her own growth curve, and her mental deveopment was way above average. She is just petite!
I say nurse him and see if you can get some prevacid and keep him upright as much as possible, in a carrier on you, or swing or bouncy seat, or try to get one of these Tucker Slings, they work wonders!
Go to a different Dr., too!!!
Good Luck! They usually grow out of reflux by 8 months to one year!