Feline hyperesthesia

My 8 year old cat has just been diagnosed with feline hyperesthesia. Out of the blue she began attacking her tail. She’s wearing a cone and taking 4 daily medications. Is it manageable? Or am I going to have to put her down? She’s miserable or she’s passed out. Tonight I took her cone off to let her clean after she eat and she licked and chewed her foot until it bled. I don’t know what to do and I’m heartbroken.