What Causes Blood Discharge In The Urine?

i have blood in my urine from time to time, about every three to 4 weeks. Hematuria. Blood goes away after 5 to 6 days. Starts out really red then ends up more pale over those days. this began Oct 4th 2011. I had a cat scan of bladder, kidneys, and ureters. Had invavsive inpection of bladder. Found a divticular on th bladder near where the left ureter enters the bladder. blood tests all normal. PSA
I thought my strenuous exercise was doing it. I stopped that and have scaled it back. I have exercised almost every day since 1991. More aerobic but am doing mor weight lifting now. But normally only dumb bell weights. My cholesterol is 200, hdl average 85 the last 10 years or more. In 1991 the HDL count was 32. total was 260. LDL is about 110.

the doctor is doing a fish test to see if there is any mutated cells that slough off in my urine.

Any way tofind out where the blood is coming from or should I get another opinion. i live south about forty miles from the University of Wisconsin-Madison. I am 60 years old.