It is still possible that your cat is allergic to even the human grade wellness food. Food can be the biggest cause of allergies to pets. All commercial cat food is "dead" and cooked at high temperatures, so it does not contain "life energy". There was a study done by Dr. Pottenger where he fed about 900 cats, some raw foods and some cooked foods. After four generations the cats on cooked foods could not reproduce and they were riddled with disease. Raw foods closest to a natural diet are best. Cats are obligate carnivores and need mostly meat, not grains and not cooked foods.
Ultimately you may want to explore the option of feeding a raw food diet. Not that is is easy, especially with cats, who are more picky than dogs. There is a good amount of literature and books out there on how to prepare home cooked diets and there are some ready to feed raw diets for cats (usually frozen). There is a good site that gives details about how to prepare home made raw foods for cats. http://www.catnutrition.org It ultimately takes time to prepare and takes time to transition a cat to raw food, but the results can be dramatic. If you want to really freak out, read the book "Food Pets Die" For by Ann Martin, which talks about the commercial pet food industry. Since you have already switched to a better food, you are already aware that better food is better for you kitty.
Otherwise you mention that you cat might be neurotic. A thought is to try Bach's Flower Essences, especially Rescue Remedy. It can't hurt at all. Put a few drops in the cat's water and see if it calms.
The other possibility is to look up "feline hyperesthesia syndrome". It doesn't sound like what your cat has, but this syndrome will cause a cat to lick incessently and remove fur, mostly on their back-end areas. Not good.
You can also give your cat some essential fatty acid oils. They need Omega 3 and Omega 6. You can try to give some fish oil and/or Udo's Choice. The Udo's doesn't give them arachidonic, but add the fish oil and you'll be good. Try a little in the food. You didn't say if you were feeding dry or wet. If it is wet, mix it in. If dry, it is tougher to get them to take it.
And then try to use a holistic vet if possible. Allopathic vets may want to use cortisone, which can be a downward spiral...
This is tough stuff to deal with all the way around, but don't give up. There are solutions.