Do you wait post bfding? I’m ebf, if I don’t wait half hour to an hour then it can make him sick.
Could it be an intolerance to something? Maybe strip it back try a veg or one allergen at a time see if it’s something upsetting his stomach
My LO did this when we first started (usually when she swallowed something) with time she now doesn’t do it anymore.
We’re in the exact same position!