At my wits end. Help!

Hey everyone. I'm new to this forum and was hoping that someone could help me with something related to my 14 year old, long hair, tuxedo cat. Emmy is her name and she has started to beg for food constantly. And I mean constantly like literally all the time. She's a small cat but she eats like she's a huge cat! So I took her to the vet to find out why and they took her blood to test her for diabetes and hyperthyroidism. The results came back negative so she has neither of those. After that, I brought in a sample of her stool to test for parasites. That also came back negative but the vet advised me to give her medicine anyway. So I did. She seemed to get better for a very brief period of time but then went right back to constantly begging for food. At this point she also doesn't clean herself as well as she used to. I've been brushing her in the hopes that it would encourage her to clean herself. She's a needy cat usually anyways and has to be around me 24/7. I play with her everyday and sometimes multiple times a day. She still has energy to run around.

The vet told me to bring her back in but I can't afford to keep bringing her in and trying different tests to rule things out. If anybody has any idea of what's wrong with her or if this sounds familiar I would greatly appreciate the advice. I'm at my wits end and feel helpless. And I feel horrible that my cat is suffering. I'm wondering if maybe she has some kind of intestinal parasite that doesn't show up in a stool sample. Do any of these symptoms sound familiar to anyone? Has anyone ever experienced this with a cat? If so do you know of anything I can do to help her? Thank you any help would be much appreciated.

This really sounds like hyperthyroidism.  A greasy matted coat is also one of the signs that can develop.  If your kitty is an indoor cat I doubt that she has some unusual parasite.  I know you said that you can't afford to keep bringing her into the vet, I certainly can understand that, but I would consider having the test for hyperthyroidism run again.

Thank you Denice. I'll have her tested again

Our girl Francie was diagnosed with inflamed bowel disease after she was constantly hungry.

Sorry to hear that Slufferk. Was there a particular test you had done to determine that?

I believe they did a procedure where they went down her throat and into her bowel with a camera and could see her intestinal track was inflamed. It was costly, almost $2,000.