Hmm, I really don't know what that could be. It's good you are going to the vet tomorrow. The only thing I can think of is that it's maybe some waste of some sort but the vet will let you know for sure. Try not to worry too much about it.
It sounds like a classic UTI. Hopefully your vet gave you a simple antibiotic course for treatment. :)
Thank you for both responses. Turns out my cat needed his sacks squeezed (?) and he had a few worms. I need to learn more about cats I guess. Seems this was no big deal.
Thanks again to both of you.
KK
Ooooh! Impacted anal sacs. Gotcha. That would be very a disturbing thing to hear. :)
fortunately it usually isn't serious, although it still sounds very disturbing. In the future, if you see him "scooting", it's a warning sign of that.