I was hoping someone would respond because my pit/boxer gets red bumps on his belly too. He had one on his ear that turned white and dry. He’s been to the vet and they said the red bumps on belly and lose of hair on legs was an allergy problem. The bump that turned white was like some other bump wart type things he has, but they aren’t white. They are just weird bumps. Ive had some of them checked because my dog has had cancer twice. You could try an allergy shampoo, and if he’s itchy, give Benedryl. You can give 1 pill per 25 lbs. I give my pittie 2 Bendryls 2x/day. He is 60 lbs.