upper left back pain

PLEASE HELP!

i'm 17 years old and i have unbelievably bad back pain. it's been going on for over a year now. a year ago i went to the chiro but it was too expensive so i quit going. it seemed to be only a temporary fix anyway - and that's not what i'm looking for. i play soccer year around, and when high school season came along this year i quit half way through the season because i couldn't handle the pain. and if you know anything about serious soccer players - you know they have HIGH pain tolerances. i started going to the physical therapist by my school. he started to work on my back and the next morning after one of my apts with him my back swelled up like a baloon. he had me go get an mri and an xray and absolutely nothing showed up. the orthapedic surgeon i saw seem like he didn't care and basically told me "it's a muscle problem, see ya." so now i'm back with black, my physical therapist. he has me doing really simple excercises but they really don't seem to be helping, and sometimes they make it worse. but i don't know if i should keep doing the excercises because WHILE i'm doing them it feels good..but it never helps later that day.

so that's my story. i really want to get this fixed!!! i'm an athlete and it's making me CRAZY not to be able to do any physical activity besides walk..and ride a stationary bike IF i can sit up perfectly straight. i've heard some people talk about how they had extra tissue and stuff floating around..and they had surgery to have it cleaned up and now they're fine. i'll do anything to make this better! i already know i'll never play soccer again:(, but i'd give anything to be able to go on a jog!

what in the world could be wrong with my back?

-bri