If the CT was clean then you probably don't need the renal ultrasound. And it is true sometimes they just can't find a reason for frank or gross hematura..but the fact that you had started a rigorous exercise program when it started...that sometimes just causes the kidneys to leak or jars the bladder.....heres a good article from Emedicine.....
www.emedicinehealth.com/blood_in_the_urine/page2_em.htmj
On a funny or became funny note...my husband after my surgery thought he had blood in his urine...went to the uro...turned out it was from a l/2 jar of beets he had eaten that day!...
But its good that you are getting follow-ups..you definately want to rule out all the bad stuff.
I knew there was a reason not to exercise...
.......Pat