thanks for your reply. She is spayed and we went away for 10 days, but someone came to check on her and sit with her for an hour a day.
When she turned nasty originally we went to the vet and the vet told us that it was because she was a calico, and she that she had "that type of personality." Now as I said before, she was the sweetest cat around when she was a kitten. She has had problems with matting because she's long-haired, and she hates being touched. But i've been shaving her belly and clipping her nails for a long time (by clipping one or two nails at a time or trying to shave off one mat).
I have an appointment to take her to the vet for her annual, so i'll bring it up again. What is Feliway? is it for aggressive cats?
As for changing her diet, she won't eat wet food, we've tried many different kinds and she won't take any treats either. The only thing she'll take is a tiny bit of plain yogurt on the end of my finger and i don't like to give her that very often.
I often thought of giving her her own room, but always felt that it would be too much like keeping her prisoner in there. She's always been used to roaming where she pleases.
Thanks again for your advice!