AB,
You sound like me 1 year ago. Perhaps my case was a little more extreme; but I had posture issues and flexibility issues. I retained a coach, and he told me that I needed medical evaluation - even though I had been cleared by a doctor, who told me that nothing was wrong with my back.
So, first, you should get thine ass to a medical professional who will listen to you and get a series of x-rays done. Those x-rays should cover your lumbar spine and hips, and thoracic spine. Make sure you don't have any structural issues before you hop on a treatment bandwagon. (When I finally found a chiropractor who listened to me, and got me x-rays, we discovered that I had a degenerated disc and an incurable spinal disease called DISH that was affecting the mid-thoracic region. This has greatly changed the course of treatment for me.)
Assuming that you check out structurally: Active Release (
www.activerelease.com lists providers in your area; feel free to PM me and we can talk about how to tell whether a provider is really good) is a good set of techniques if done properly. Basically, the goal is to identify muscular impingments/adhesions, where the muscle is bound up to the fascia or otherwise constricted, remove those adhesions, and permit the muscle to move in it's full ROM. Such treatment can be quite painful.
My condition is such that I've been getting 2 ART sessions per week for about the past year. I owe my life to my ART provider; he's literally turned my body around, despite my spinal disease, and has enabled me to train hard. I can't say enough good things about therapy; so, I'm quite biased, and in some ways the best and worst person to ask about it.
The T-nation articles are a decent starting point for some at-home work.
If you're serious about this, you're going to have to stretch daily. Consider getting into Iyengar yoga; the Iyengar schools is built on concepts of body-awareness, and will teach you well how to listen to what is wrong with your body, and to work on correcting it. I do weekly 1-on-1 sessions with a veteran Iyengar coach. This has helped me to take what the ART therapy does, really understand it, and then work to further it at home.
I'll leave you with this tidbit for now: in every back exercise involving a contraction (rows, shrugbacks, back extensions, pulldowns) keep your chest up, and pause at the contracted position for 2+ seconds, and squeeze the motherfuck out of the mid-back musculature. Really feel all those muscles contracting.
If you have any more questions about this, please do not hesitate to ask me. I'll help you out with honest answers about my experience as best I can.
Best of luck in your journey.