Your description could have been written about my son at that age. At first, they said reflux and put him on zantac. I saw no improvement. Then they put him on Prevacid for silent reflux. I saw a LITTLE improvement. But, the more research I did, I found that with reflux, the baby is usually upset AFTER (or at the end of) a feeding when the gastric acids are bubbling over, so to speak. My son NEVER cried AFTER, but DURING! He would scream and cough and arch his back. He would take an ounce or so, then scream, then want more and we'd do that over and over again. He did feed better when really sleepy, like dream feedings. But otherwise, it was difficult.
What I would recommend is to take him to Pediatric Gastroenterologist. We waited until our son was about 3.5 months old to call and get an appt. It was about a 1.5 month wait for an appt and then another month to get testing done. It turns out that our son has Dysphagia and a bit of reflux. Dysphagia is a swollowing problem and there is A LOT that can be done to help them (and train us as parents how to help them). But, Pediatricians are not trained to recognize let alone diagnose this. It requires a video swallow study.
It's no big deal, no meds are even involved (unless there is reflux) but my advice is don't wait. Our son was 6 months old before we had a firm diagnosis and his struggles with eating during that time caused him to drop precentiles in weight and generally struggle with eating.
I would recommend Cincinnati Children's Medical Center's Interdisciplinary Feeding team. They have SEVERAL specialists that work together (including a Ped GI, speech path, etc). to both find the problem and map out a plan of what to do next. It may not be near you, but maybe there is one closer. I know people travel very long distances to see them, they are just that good.
I'm certainly not saying this is what your son has, or anything. I just want you to know that it might be silent reflux, or it might be somthing else and a Ped GI is best equipped to make the right diagnosis and recommend the best treatment.
If you have any questions, please PM me!!
Jenni