I would reccomend taking him to a veterinary dermatologist--they have the most expertise in issues of the skin, and the part of the ear that is causing problems is the skin. I wouldn't expect allergies to occur in such a young pup regardless of where they are or what they're exposed to, but there may be some other skin condition. If a scraping/culture doesn't give the answer, the derm may be able to do a punch biopsy.

Good Luck.

Jakesmom