Idiopathic hypercalcemia cat

My cat, a 3-year-old domestic shorthair, was diagnosed with idiopathic hypercalcemia a few months ago. She is undergoing daily subcutaneous fluid treatment and has recently started taking Alendronate once a week.

I'm feeling pretty overwhelmed at this point because she isn't eating, and her weight is fluctuating unpredictably. For example, a day ago, she weighed 2.6kg before her subcutaneous fluids, but it dropped to 2.5kg after. A week ago, she was 2.8kg, and before her diagnosis, she weighed 4.6kg.

I'm seeking advice from anyone who has had a similar experience with their cat. How is your cat doing now? Over the past few months, I've spent almost $15,000 on her hospital visits, check-ups, treatments, and various expensive diets, hoping she would eat.

Can someone offer pointers on what I should do next? Her ionized calcium levels were around 1.8 to 1.9 two weeks ago. The doctor administered an IV treatment for 3 days and prescribed 1/4 of a Prednisolone tablet.

Currently, she weighs 2.5kg and is very picky about food. She tolerates Hill's K/D Wet Food and reacts well to snacks from a brand called Bionature. I'm hoping she will also like Royal Canin Renal wet food. She isn't drinking water on her own, so she's receiving 200-250ml of subcutaneous fluids daily. Since she enjoys Bionature snacks, I'm considering mixing them with Hill's K/D wet food, but I'm unsure if that's a good idea.

Any advice would be greatly appreciated.