What causes blood in the urine without a uti,and will it clear up by itself?

Micro-hematuria: Microscopic hematuria is fairly common and often from a benign familial tendency. Unfortunately, blood in the urine is also often the only sign one gets from some conditions that need to be discovered, like bladder or kidney cancer or kidney stones. See a urologist for workup. It likely will involve an office cystoscopic exam and upper urinary tract imaging.