Question

I adopted my cat, Tigre,female. about 12 years ago, didn't know how old she was then. She was quiet and didn't socialize much until about 3 years ago (we now have 3 other female cats, 2 of which were adopted a year after Tigre, the third was a stray we brought in a year ago, had her fixed). End of last year, she started to lick her back by her tail until she was almost bald. She also started drinking out of the toilet a few months back. Always had a pretty big appetite for dry and wet food treats (about a tsp twice a day). Suddenly she started following me around, "yelling" at me and won't eat but a few tsps a day and won't drink much water or tea (she also started drinking tea a few months ago). Her eyes don't look right, kind of sad like she's trying to tell me something. I have tried different kinds of wet food and even baby food to get her to eat more, I pet her, brush her and talk to her. She still won't eat much and looks sad. I don't have alot of money to take her to the vet and have some tests run, I know they're expensive. Please help, I'm afraid of losing my oldest daughter.