Save Mr. Jinx

My cat Mr. Jinx is three years old and is suffering from a most unusual, debilitating skin condition. He is constantly scratching, never with a moments peace, and has removed much of the fur from his legs and around his ears. His little paws are so cracked and dry from being constantly chewed that the vet has recommended he be kept inside, relatively immobile. Sometimes he scratches so profusely he creates open wounds and has to wear a cone on his head and feel even more miserable. After numerous visits to the vet, we have ruled out more usual causes such as a flea allergy, topical fungal infections, and other ubiquitous allergens. But this hasn't brought Jinx any comfort and he is still suffering and his condition is only deteriorating. He needs an operation so as to take samples from the affected areas and analyse the cells, but I am a full time student and it is well beyond my financial means.