My baby is struggling with his feeds when born was

Patient: My baby is struggling with his feeds when born was drinking 2oz milk n slowly changed to 3 after I tried giving him 4. But he would never take it he is now 6-7 weeks and has totally gone down to 1oz milk he is so fussy with his feeds and cries when the bottle goes to mouth he cries when swallowing the milk but you can tell he wants the feed he poos with difficulty

Doctor: