Baby crying during bottle feeding

My baby boy is 4 weeks old and last few days he started crying midway through bottle feeding.

At first I thought it was frustration that he couldn’t get the milk quick enough so moved from size 0 teat to size 1, but he is still doing it. He is definitely as he takes the bottle so eagerly.

I thought may be a wind problem so have started Infacol last night and I always am sure to burp him a couple times during the feed as well but nothings helping. I’ve tried bicycle legs, rubbing his belly and there’s been no change in his poop at all.

Poor little guy seems so upset and I really don’t know what’s wrong with him 😩

Anyone had this and have any advise?