Our 3.5 month old baby (corrected - 5 weeks premature) is really happy most of the time but over the last few weeks during feeding he cries a lot and seems very uncomfortable and due to this he hasn't eaten much. This is the same if he is breast or formula fed. We have to keep offering him the milk until he's had enough and stops crying and as soon as he stops eating he's very happy again. He was born low birth weight due to preeclampsia and has been growing well since then but he has barely put on any weight over the last few weeks.
Common problems have been mentioned by both our GP and health visitor like silent reflux, colic and allergies but they expected him to show symptoms outside of just feeding time for example when lying flat but he doesn't. We always burp him and he seems to burp well but hard to know if he still has wind. He starts crying as soon as he starts eating, not just once he's finished which makes me feel like it's the feeding process that's the problem and not something inside him like wind. But it's so hard to know.
I was wondering if anyone has experienced anything similar or can suggest what the problem is?