She gets a tablespoon of pumpkin a day. More than that gave her gas pains, and less than that didn't seem to do anything.
We haven't tried probiotics. My mother is the main caretaker of the cat and isn't open to totally eliminating dry food (she thinks only eating wet food causes diarrhea). I'll look into Slippery Elm.
The steroid/anti-biotic course was over a month's time. He tried another antibiotic a month earlier and after a few days, it seemed to be making her worse. I assume that's why he didn't go for a two-month course this time.
She was last weighed five weeks ago at around 7 pounds. She lost two pounds between April and June after a few diarrhea and vomiting attacks. I don't know if she's gained any weight, but she doesn't seem to have lost any either. Her fur is much thicker since switching food, and her eyes are also clearer.