I had a cat, Marina Mar, who had that same problem. Has Pumpkin lost the hair around and on his ears??

Marina Mar was diagnosed with Pemphagus Areolus. It's an immune problem that causes the body to kill any new skin cells. It took us a LONG time to figure out what it was. It was so advanced that it was also in her nail beds. The scabs on her ears were very painful. You might want to ask your vet about it.

Please keep us posted.