Hi...My Boyfriend Is Having Problems In His Lower Back Right

Hi...My boyfriend is having problems in his lower back right where his kidneys are on both sides. He says they feel like they are bruised. He says it is a constant dull aching pain that stays for weeks at a time then goes away. It burns when he pees and sometimes feels like he has to pee but can't. He also says sometimes his testicles hurt as well. What could it be?