Saving Tydus the cat

Hi everyone ive had a cat for about 11 months now. and his tail has become dead and hes in alot of pain the doctors dont know ive paid 330 dollars and they vet doesnt seem to be using it to help him i owe 250 dollars and im on a very bad income i can hardly scrape by with life. the pet was given to me by someone and idk why but ive been having problems i have no income till the 25th. I really need help anything counts