Hello-
Is your cat spayed?
Thank you for the additional information. Given your cat's age, I would definitely take her into the vet for a check. It sounds like she may have a pretty severe urinary tract infection going on and your vet can put her on antibiotics to clear it up. I would also ask your vet to check her stool to ensure there are no parasites causing this problem. I think your girl will be fine once she gets on antibiotics for a week or 2.
Please let me know how things turn out and if I can help further.
Feline Healthcare
16 yrs health care mgmt & issues relating to cats, reproductive issues and multicat environments