I would call your vet right away. It can't be comfortable to your cat. He/she is probably driving herself crazy. I'd hate to have that go on with me. Maybe she has fleas but it sounds like she could have some kind of allergic reaction going on. It has to be something. Maybe she got into something you don't know about or ate something. I would suggest you get him/her re-checked again or at least call your vet. They should have an after hours line you can call. Maybe there is some kind of medicine you can give her or cream. Good luck to your poor cat. I hope he/she gets better soon. Take good care of him/her.