my son s back (lower right) hurts while urinating and for a shor time after he urinates. the pain is severe and lasts for about 5-10 minutes and then disappears. he has a history of holding his urine (does not want to stop what he is doing). seems he is at it again. last year, he had urine in his blood. he had a few ultra sounds of kidney/bladder/etc., which did not show anything unusual. ultimate conclusion is that the blood seemed to be caused by the stream being so strong when he did relieve himself, that it caused fissures in his urethra. he did not have the back pain last year, that he is having this time. he does not seem to be carrying a fever. i have not yet detected blood in his urine. please advise.