My cat had the type of swelling you're describing and it was a fungal infection. Vet diagnosed by pulling out some of the fluid with a needle. This was not done in front of us, but I gather it's a fairly quick and simple procedure. A little expensive, but wouldn't we do ANYTHING for our babies?
You sound like a wonderful mom!!!
Best of luck!
You really sound like a great mommy/daddy!! I can't tell if you're male or female! It really sounds like you need a new vet. Your cat may be 20 yrs old, but with her beautiful blood work, she is no where near ready to die. Your vet shouldn't be giving up hope either, especially since she's so active.
I'd take her to another vet and get that swelling checked out. I'm not totally sure what it is, but I DO know that there are sinuses located above the eyebrows, above the nose, and underneath the eyes. Maybe some of those sinuses are filled up, and possibly infected. Just an idea!! They might be able to do an MRI to see what's going on. That will be expensive though, but if you can swing it, it might be a good idea!
Please come back with an update!!
PS-I'm so glad that you're force feeding her and making sure that she's getting enough fluids, and keeping her in a humidified room. Those are all of the things that me and some others would have suggested. You ARE doing everything right!! Your cat is lucky to have ya!