we have a 1 and a half year old male jack russel terrier - pistol pete! twice in the last 6 months he has developed a sore near is butt hole. it eventually scabs over and heals. he does lick it and favors it so i believe it is sore for him. we feed him good food, and very little table scraps. he loves dingos and gets one every other day. any ideas would be great?