Back and bowel movements

I am a 16 Y/O male and RECENTLY out of nowhere started expieriencing dull lower back pain and dull pain before going #2.. i have read alot on the internet about back problems and can relate to lots of them and sypmtoms other people have. I am into boxing but dont know if that plays a role in it. Could this be a problem with the LUMBAR section of my back, or constipation? Please help before it gets out of hand. Thank You.