Frank -
It sounds like it could be kidney stones. Some people get a lot of them, and if you can't pass them, they irritate the kidneys as well as the ureters leading from the kidneys to the bladder, or the bladder and the urethra, thus the blood.
The antibiotics will keep you from getting an infection, but they won't solve the main problem if it's stones. I think you should definitely see a nephrologist without delay.
[This message has been edited by SamQKitty (edited 05-18-2002).]