Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry to hear that Grim has dry skin coming from his ears and that they are itchy.
Ear mites would certainly be one possible cause of what you are seeing. Depending upon treatment it may take several days to a week or so for him to get some relief. Ear mites generally cause dark waxy debris in the ears though, and you aren't reporting that.
I would recommend an examination by your veterinarian to look for other contagious diseases. I would take a swab and scraping of the ear skin to look for evidence of mites, sarcoptic and demodex, and collect material for a ringworm culture as these are the most common causes of increased dry skin and itchy ears affecting cats. Sometimes mites can be difficult to find, especially in early infestations.
Other less common reasons for dry skin and hair loss are related to endocrine diseases such as hyperthyroidism, or Cushing's Disease (an overactive adrenal gland). Testing is done via a complete thyroid profile or just a T-4 for thyroid disease and an ACTH response test for adrenal disease. These would be very uncommon in such a young cat.
Autoimmune skin disease (body attacking itself) is a possibility if his ears were crusty and ulcerated along with increased scale. Diagnosis is via a skin biopsy. Treatment is immunosuppressive drugs such as steroids.
Finally a condition called Feline Pinnal Alopecia is possible, but less likely. This occurs most commonly in Siamese and Siamese mixes. The hair loss areas are smooth and not itchy. It may be patchy or involve the entire ear. Hair may spontaneously regrow.
Treatment is usually unrewarding but some recommend Melatonin orally at 1/4mg per pound of body weight every 12 hours. That's 2.5mg per 10 pound cat every 12 hours.
At this point given his young age I would be most concerned about ear mites, skin mites including demodex and sarcoptes, and ringworm. An accurate diagnosis is important because ringworm is zoonotic, meaning it can be passed people, and each if these conditions is treated differently.
Best of luck with your kitty, please let me know if you have any further questions.