My bub was doing something similar but only when he fed on the right side. I went to a LC and she suggested it was because he was uncomfortable.. I tried their breastfeeding cushion and he latched on and fed happily for over an hour He is quite a big baby and i guess he just couldn't get comfy enough.
I have bought myself a cushion now and things have dramatically improved for us.
Good luck, does your CHN have a LC service??