Thanks for the reply. I've never had any sort of physical accident. I was under a lot of stress during that time, but there was no injury to account for all of this.
I can't remember how much my back cracked when I was 16 but I did have to visit a doctor for muscle pain (shoulder and neck). He referred me to a physical therapist who essentially told me I had bad posture and a weak upper body. I'll admit I didn't have the best posture, but I can't say I know many people that did. The therapy didn't help too much. I've been trying to improve my posture over the years, but I'm still having pain, so I am loosing faith in the "bad posture" diagnosis.