back pain cause ?

I have had back pain since August of this year. I am 23 years old, 151 pounds, and no other health problems. In August I started walking on my treadmill and had been for about a week when the lower back pain started. I was only hurting in my lower back and had been for a week when my boyfriend, Clint, suggested I try a chiropractor. I had never been to one before and decided to give it a try. I picked one out of the phone book and made an appointment. At the first appt, he gave me an assessment and determined that my pelvis was out of alignment slightly but I had no other structural issues. He said he didn't really think that was the cause of my lower back pain and that it could have been a combination of things. He said that most people need about 6 or 7 sessions to get better. After that session, I started hurting again as soon as I got home and a friend of mine told me that it was normal to hurt a little after the first couple of sessions because the muscles aren't use to it. I didn't understand that fully but ok. Since I had been going to him, the middle of my back was hurting. It had hurt everyday and didn't stop after a couple of sessions. That is when I started to doubt the chiro because I thought a person wasn't supposed to hurt worse and in new areas after starting treatment. After the seventh session, Clint told me to try another chiro so I made an appt with a chiro that was recommended to me. After the first adjustment and assessment, he said that the first chiro may have over adjusted me but he couldn't say for sure. I was still in a lot of pain after a few sessions with him so he suggested that I see a medical physician to get an anti-inflammatory and continue the sessions with him. I found a physician and he prescribed a steroid, an anti-inflammatory, and a muscle relaxer (which I can't take because I have a full load of classes and need my wits, not drowsiness). He suggested, but not ordered, that I consider not going back to the chiro. I have heard of the "silent feud" between medical doctors and chiropractic doctors, though I don't know if that was the case here. I ceased and started the physician's treatment. He had also taken an X-ray, which showed no abnormalities, and checked my mobility and range of motion to determine I had no problems with my disks. My pain had not gone away by the next appt with the physician so he suggested that I try physical therapy. I made the appt for a week and a half later (delayed because of school). About two or three days before my appt. my back had stopped hurting. I didn't know what happened but decided to go to therapy anyways because I wanted to make sure the pain didn't come back and to see if I could find out why it had hurt in the first place. The other three were unable to tell me so I figured the therapist might be able to. The first week of therapy was pain free. In the second week, my lower back started to hurt again. It was more of a tightness and discomfort than pain. In the third week, my middle back started to hurt when I was in classes (sitting down). At the end of the third week, my therapist reassessed and wanted to try a method called traction. He said that it usually helps people with back pain. It has so far hurt worse than before it was used. Started to hurt Friday (first day of use) the 31st (Halloween). Saturday and Sunday mornings were awful. I was in so much pain, I couldn't sleep, sit, stand, or lay down. Every position was painful. The pain decreased a little during the day but was still bad. I don't know if I pulled a muscle during the traction or what even causes my pain. I am tired of it hurting but am more tired and fed up with not knowing why. All of the doctors couldn't tell me why and I know that pain doesn't happen for no reasons. I have been asked about stress levels, shoes, posture, sleep, etc. and no questions brought any concern to the doctors and gave me no answers. I appreciate the doctors that have tried to help me and I know they are very well educated. I am just frustrated and currently in pain. I have taken my first muscle relaxer tonight and it must not have kicked in yet. Basically, I would appreciate any insight, suggestions, or advice. I am tired of spending so much money and just want an idea of what may be going on. Thank you for taking the time to read this.