Baby will only eat while drowsy

Hey everyone,

So from about 7 weeks on, my 3 month old will ONLY eat when he is drowsy and about to go to sleep. He does have a full feed when that occurs but I'm starting to get concerned.

I'm worried that he is very sensitive to something I'm eating (Ebf) and is "stressed" when it's time to eat because hes in pain (I've cut out almost everything because there has been blood in his poo).

Or could he just be used to ONLY eating when hes tired? Anyone have this?