Does anyone know the signs of a urinary tract infection in female dog? At first I thought she was just in heat, but she is spayed. She is constantly rolling over on herback and licking herself, even on walks.

Does anyone know anything about this kindof stuff?
She also has a faint brownish discharge, and it seems like she is very sensitive in that area. She is an inside dog. I has been going to the bathroom less that usual.