What Causes Blood In Semen And Stool?

my son is 21 years old. He has been having blood in the toilet when having a bowel movement as well as blood in sperm. This has been going on off and on for months. He was treated for a UTI and it went away, now the stool. He pulled his groin at work months ago and I took him to the ER they gave him pain pills and sent him on his way. No tests whatsoever.