Bring Nikita to the vet - they can check for mites that are WAY too small to be seen with the naked eye, and can especially cause itching around the ears. I wonder if maybe the maker/distributor of Dermoscent might be compromising your vet's objectivity - a second opinion might be helpful.

Be careful with the hydrocortisone - I tried that on Smudge, and it made his fur fall out! I was rubbing his considerable bald spot with emu oil for weeks after, just as protection and to get the fur to grow back (and yes, I let him lick plenty of it off my fingers too, as it's supposed to be an OK skin/coat supplement in and of itself.)

The biggest improvement I saw in Smudge's allergies was when I kicked all the grain out of his diet. I also can't give him tooth-cleaner treats - they all have aspergillus niger in them, and I think mold is one of his problems (his face still gets itchy in the summer). The vet prescribed chlorpheniramine and prednisolone, and he's usually pretty comfortable these days. He's got all his fur back, and doesn't mat up in the muggy summer weather.

But Cornish Rexes are their own breed, and a vet will have a lead on what they tend to be allergic to and what approaches they respond to best. (Smudge is a "Mainely Coon," looks and acts like a MC but has no pedigree.)

Also, be careful with the tuna - humans' nutritional needs are very different from those of cats, and too much ordinary tuna can cause health problems. Be sure to choose a brand like Solid Gold or Soulistic that's formulated especially for cats, with extra vitamins and minerals that cats in particular need to stay healthy.

But first, definitely, the vet, to rule out mites and breed-specific conditions.

Pets and cuddles (and kisses, if they'll have them) to your kitties! Can we see a photo?

Love, Columbine