Have your vet do skin scrapping's to test for "scabies". This is contagious so if you have other pets be sure to isolate until it is under control. This is also a mite and similar to mange in dogs.
Your vet may need to treat your pet with sulfa dip washing--the entire process to resolve may take at least a month.
If your cat is an outdoor cat this is probably where it was contracted. Just make sure until it is resolved your cat is isolated from other animals.
Let us know how you make out at the vets.
......and I am surprised your vet did not already test your cat for this along with the ear mites--two different critters but very closely related.
Hello and welcome...In reading your post I had a feeling you had a white kitty...and you do. If it is indeed the white one you're talking about, the issue *might* be a cancer called Squamous Cell Carcinoma.
Here is a photo of Jade's ear that was dx'd with SCC. Does your kitty's ear look anything like it?
Hey, Jade, does someone need a special link to open that photo? All I get is your main page.
To TMT2 -- it could well be skin cancer. Not life-threatening but will need treatment. Or it could be a precancerous condition. Skin cancer on the ears looks like sores that are pretty bloody and they might heal for a while but then come back again in that spot.
Shoot, I thought I had set that photo on public, but apparently you have to set it in more than one place for it to stick! I'm glad you asked so I could make it right. I opened a couple other photos to public with one where you can clearly see the scabs on Jade's ear tip. It's on her right ear, but left in the photo. I opened the one after her surgery also. Please let me know whether or not you can see the pic.
I hope it's not cancer too but it sounds EXACTLY like what we went through with Jade prior to surgery. The scabs would heal up, then come back. Finally they began to bleed...as you'll see in the photo. That was when we knew it was time to have her ears amputated.
TMT2...are you there?