18 yr old Cat with IBD

[RGW]

I have a cat that recently turned 18 that has dealt with irritable bowels for around 3 years. She goes on a treatment of antibiotics every few months, and while there are accidents, she tends to do okay.
Lately, however, she seems to have lost even more weight. And her stool has been liquid for several days now. Her diet mainly consists of Fancy Feast Classic with mixed-in pumpkin. She also eats baked chicken, and sometimes chicken and rice mixed together. She was put back on antibiotics a few weeks ago, but her condition hasn't improved. In the past few days, her eyes have had a brown discharge. She also doesn't seem to have as much energy, although today she was a bit perkier.
Are there any other suggestions? The vet has also tried giving her a steroid, but that only seems to make her diarrhea worse.