I think you should take time, but switch the kitty over to a good quality wet food gradually. Do some research into it.
It has been a long time since I have used canned cat food. I make my own raw food for our cats, and have been for years, but its not everybody's "cup of tea". So the next best thing to do is go for quality canned.
One of the major reasons for it is because of the moisture content. With cats being a desert animal, they rely on their food for the moisture content to maintain the body. Consequently cats have a very low tolerance to thirst.
If they are on dry food, they are constantly dehydrated to a degree. To demonstrate this point: when my 3 cats were on dry food, I was getting between 59 and 69 days out of a 40 pound bag of cat litter. Now that they are on raw diet, the same 40 pound bag, I get between 50 and 54 days on it.
So this will give you an idea of how dehydrated they were on dry food.
I am not familiar with grizzly salmon oil. I tried to do some research on it today, but it still leaves me in a bit of a quandry. Fish oil has a tendency of going bad relatively quickly when it comes in contact with air and I noticed that the grizzly salmon oil was in a bottle with a measuring spout. I'm wondering if something has been added to keep it from spoiling, and if so, what.
When I was looking at the amount of DHA and EPA in a serving, it was related to one measured squirt, but gave me no idea of the mg of the serving.
Basically what I use is Carlson Salmon Oil, 1000 mg softgel made up of salmon, anchovy, sardine and mackerel with a DHA of 90 mg and EPA of 110 mg. If you decide to go this route with any supplement from a health food store, make sure that that is all it contains. And be sure it's not flavoured. If you go with the Carlson somewhere down the line, start with a small amount - maybe 3 or 4 drops per meal to start with and work it up gradually. One of these softgels when opened with a push pin will give between 26 and 28 drops.
I've had good luck with it. My cats get 14 drops morning and night, so each of them gets a soft gel a day, and it is mixed into their food. That's why wet food makes it easier.
Can relate to your weather problems. We picked up a portable humidifier and it sure makes a big difference for us as well as the cats. Nobody receives a shock every time you try to pet any of them.
Regards to stress - if there is stress in the house among the humans, this will be picked up by the animals - cat, dog, or bird - and cause them to be stressed as well. Just moving furniture has a tendency to stress them out as well - we have one that creeps up on stuff to make sure it's the same thing that was somewhere else.
Something I'm trying at the present time is music for cats. And I find that this seems to have a calming effect on them, especially if we're going to be out of the house for any length of time. It's really not my music, but it works for them. If you want to try it, google "free music for cats".
Here's a web site that is well worth bookmarking for future reference.
http://catinfo.org/
On this web site, some of the highlights that might be of interest would be - Urinary Tract disease, Pilling cats and dogs safely, Transitioning Dry Food addicts to Canned food.
Hazel mentioned Thyroid. With the amount of time you've been to the vets, with blood work done, if so was there any sign of problems there?
One last thing. You might want to google is Feline Alopecia, and see if any of that info fits your problem.
Hope this info is a help to you. Sorry for the length of the post.
Keep us posted, and pictures of your kitty would also be appreciated.