From the distress you are mentioning, try to rule out all things, and eliminate one at a time ...you may just have to play detective...feed the baby in an upright position,...try burping 2 or 3 times during the course of a feeding...babies gulp air when they ar...
Try going on an elimination diet: I had the burping, the feeling of irregular heartbeat and the tight feeling in my stomach for a long time, along with the bubbles and the feeling of discomfort in my throat: though I never knew it, I was allergic to wheat and a host of...