We have a really loving cat that has had relatively few problems. He came from a shelter, so I don't know his exact age, but probably about five or six years old.
One day I was petting him (he came to me to be petted) and as I stroked his back, he went into a maniacal fit, biting both me and himself, and had to be pried away. I received several deep wounds.
I had a lesser event a week ago, and then several days ago it happened to my wife. The cat had climbed on her as she lay on the sofa, and she was petting him and made the mistake of running her hand down his back. He went totally crazy and did enough damage to her thumb that we had to take her to the E R 30 miles away.
If I'm really careful, I can induce the same thing at will by stroking his back in the right place. I stand as far away as possible, because he goes into a horrible fit that lasts about 10 to 15 seconds. He seems to have no control at all. It's scary.
This is a cat that is normally affectionate and a real lover. Now I'm kind of afraid to hold him anywhere near my face, and have to be really careful how I pet him.
I do not have a lot of money that I can spend on getting xrays and doing diagnostics. I need help. And so does my cat.