The probiotics didn't help after a week - made her a bit worse.

Broke down and ordered a case of Wellness canned - chicken. Here's hoping. First feeding in an hour and a half. I'm praying for no vomiting and/or abnormal BMs. Otherwise I hope I like the taste because someone will have to eat all of that ~$30 cat food!
I'd love, after the past six months, to have a reliably available food she can eat with no problems. I've sure tried.

"When you choose the lesser of two evils, always
remember that it is still an evil." - Max Lerner
Make sure to transition from the old food slowly by mixing it with Wellness. (Otherwise, you might have more tummy troubles.) Continue to give probiotics. They won't hurt her and may help long term.

Warm the food a bit before you feed her to tempt her senses. At her age, her sense of smell has diminished.
Good luck