I would guess as a mum who has seen this in my own kids that he is habitually licking the top lip, which is continually making it sore and it's the pattern he needs to break. I'd go to the pharmacist and get an opinion on the best topical treatment. I've found sometimes creams just compound.tjr issue. Please, please, please don't put any kind of steroid (hydrocortisone) cream on his face unless specifically directed to by a Dr.