Update

The antibiotics seem to be reducing some of the infection. She continues to have trouble eating and sometimes has trouble breathing also because of the growing tumor. Just a week ago, she would happily slurp away at her Trader Joe's Turkey and Giblets catfood and now just turns her head away at it because even that is too lumpy and gets stuck in her mouth. I've switched her to Gerber babyfood and lactose-free milk. Apparently babyfood must be a popular thing to feed pets because the cashier asked me if I was buying for a kitty or a doggy. At first I took a bit of offense that this stranger automatically assumed I wasn't a mother, but then I realized that real moms probably don't buy only the babyfood flavors that are all meat.

She also has blackish, liquidy poop, which is a sign of ulcers.