Should I get a second opinion from a different vet regarding my cat's hair loss, dark spots in ear and scabby skin?

Please note that I'm not a vet, but I once had a cat that went missing for some time and came back with a very severe ear infection including mites.

The dark stuff in your cats ear is ear wax and the color is absolutely normal. The skin inside the ear doesn't look reddened either. If you want, you can clean it with a wet cotton pad. Do not use cotton buds / Q-tips on animals because the risk of injury is too high. Instead, wet a cotton pad with warm water, squeeze out the excess and swipe the ear in a motion that mimics another cat licking the ear.

If your cat had mites or any itchy ear infection, the hair loss would be centered right in front of the ear and on the cheek. Infections like these affect the inner ear, which is situated inside the skull behind the cheeks. The edge of the outer ear, where your cat lost hair, is too far removed to expect hair loss as a result of infection.

That said, the skin of his ear sure looks dry and slightly scabby. When our cat had his severe infection, he scratched his cheek until it was raw and bloody. Our vet gave us an oil that we applied to the raw skin, which kept the skin moisturized and lessened the itchyness. We also fed him an oily food supplement that kept his fur very smooth and shiny. Maybe you can help your cat the same way, either with products from your vet or with small amounts of coconut oil _(PetMD).