thank you for all your help ^_^

she is not straining then as she remains quite motionless, tail not twitching, just as if she's waiting for something to happen!

I don't think I made it clear that she only started getting blood in her pee again yesterday - I thought the antibiotics were clearing it up. It was about 2.5 weeks ago that I took her to the vet and she was put on medication. The blood disappeared from the urine the very next day... it returned yesterday about 2.5 weeks into the course of antibiotics. It's just WEIRD!