Rosie,
I read someplace, I believe on this website in the section on food, that salt is the last of the tastes to go, so if for some reason, something was damaged, maybe the only taste you have left is salt, although why that would occur after a tonsilectomy I have no idea.

I had this same problem 9 days into radiation. Everything tasted so salty I could not eat it. I lived on Ensure Plus coffee and butter pecan flavors. For some reason these did not taste salty. If you are trying to eat canned soups they probably contain a lot of salt exacerbating the problem. Try putting a raw potato in the soup for a few hours to draw the salt out of it. I think the first things I could finally eat that didn't taste salty were scrambled eggs, cream of wheat made with water with hot milk, butter and honey on top, apple juice, apple sauce, salad, turkey, steak. Took forever before I could taste sweet stuff. They did give me zinc and a bunch of other vitamins to promote healing.

Go see your doctor. Maybe it is a little blood like Gary says. Hopefully this resolves it soon. Meanwhile try some Ensure Plus or Boost Plus or make one of those 1300 calorie shakes so that what you do manage to get down is full of protein and calories. You don't want to lose more weight too quickly.

Take care,
Eileen