What Causes Blood In The Urine?

I started testosterone replacement therapy (due to hypogonadism) for low testosterone levels, taking 30 mg Fortesta gel each day. I also had prostate surgery 5yrs ago, and radiation for same 3 yrs ago, and good (zero) PSA's since then. I started the gel therapy about 3 1/2 wks ago, and have also been exercising somewhat vigorously recently. About 2 wks ago, I notice blood in my urine that went away same day...and again about 2 wks later, which also went away, although I noticed what appeared to be some clotting. Can testosterone replacement therapy cause this type of occurrence, or the excessive exercise, or both? I also finished 4wks of antibiotic for bronchitis about 2 months ago, not sure if that's relevant. All days otherwise urine has seemed normal.