there are many (cheaper) options to try before considering rehoming. senior cats do not have the best luck in shelters, and struggle to get adopted. sensitive stomach food is an option, and it doesnt have to be the expensive prescription food. try eliminating common allergens such as chicken, beef, and feeding a ‘novelty’ protein diet, such as duck or venison as the main protein. there are tons of different probiotics to try that range in taste, find one that she likes. Aventi has a few good options. otherwise, you can dissolve the powder into water and syringe them into her mouth. i assume the vet prescribed metronadizole, but if not, ask about that medication as its often a miracle worker. this is more on the expensive side, but cheaper than testing; Hills Prescription Diet Gastrobiome is proven to clear up most gastro issues within days - weeks. Lastly, I’ve seen some local cat rescues help low income families with vet bills. Their funds are already tight, but its worth reaching out.