Thanks for the quick response. I am taking her to the vet for a work-up because of this on Saturday. She has been spade, many years ago. The vet did recommend Proin. I forgot to mention that my boyfriend was given a "sample" of this drug and discontinued it after only two days. I was out of town (which is good as I would not have approved of her taking this without a checkup first) but apparently she started drinking water excessively during those two days and peed on the kitchen floor right in front of him once, which as I mentioned she never ever does. Though other than that she has been acting normal. I wanted to take her to the vet today but I just moved and the only vet in my area can't see me until Saturday.
Thanks again. I'll certainly tell the vet your recommendation.