Before this problem occured did you clean the wrinkles frequently? If not than that may be the cause. Even though you are feeding a good quality food your dog may still have a reaction to it. I beleive Hills is not all that great (if I remember correctly) I think it contains quite a bit of corn products? Also plastic feeding dishes are known to cause skin irritations (red, raw, pimples etc..) around the mouth area. If he is eating out of plastic I would switch to stainless steel. He is a cutie! Good luck!