Okay,
I googled rash and bladder and can't get a hit. :-X
I even googled psoriasis and bladder and didn't get a hit.
My only question is this...
IS THE DOCTOR PLANNING TO BIOPSY THE SITE? IF HE DOESN'T BIOPSY THE SITE, THEN I THINK HE NEEDS TO PROVIDE YOU WITH THE PROPER NAME FOR WHAT IS IN YOUR BLADDER!
What this brings to my mind is when my sister saw the photos of my bladder cancer, she said, "That looks like psoriasis." (We both have psoriasis) There were obvious tumors also.
The doc just gave her a glare. >
Anyway, I'm not saying that you have bladder cancer. But, I think you deserve a name for whatever it is that you have. If it doesn't have a name, I think I would insist on a biopsy or a 2nd opinion.
Blood in the urine has an organic cause. Saying you have a rash just doesn't cut it. Not to me anyway.
Good luck and please keep us posted.
Rosemary