K.L.
Show it to the Dr just to find out.. But,is there a chance he is teething and chewing the inside of his cheek to relieve some tension in his jaw? Or maybe hes sucking on his tongue on that side,, just a habit maybe? When he eats, does he chew more centered? Give him a cup and see how he drinks. Is it off to the side, or full mouth? My grand daughter chewed the inside of her cheek for a while. She had a big pimple/bug bite on the outside and I think it was sorta itchy inside and she was scratching it,,I dont know, it just seemed like thats what she was doing. It went away and she doesnt do it anymore.