I would take him to the vet. There are many things which can cause hair loss - demodex (mites), ringworm, hormonal imbalances, flea allergies, just to name a few. I think you would need to have him evaluated by a vet to determine what is causing the hair loss, itching and red ears and prescribe proper treatment. I had a chi once that was allergic to flea bites, and even one or two fleas on her could cause all sorts of problems. Poor baby, you know he must be very uncomfortable. Keep us posted.