My Husband Is 30yrs Old And Has Been Having Blood

My husband is 30yrs old and has been having blood and blood clots in urine for 12 years and has been through all the test with the urologist, still we have no answer! I don't know what to do next. Its painful for him and he's tired of it. It usually occurs unexpectedly during or after intercourse. Then sometimes he is unable to urinate afterwards. I just want to know your thoughts on what it could be or what we could do next. Thank you.