JS, I had no accidents and didn't get hurt in any way - it just appeared, and for a few days felt like a minor muscle pull in the thigh that I was hardly aware of, then after about a week the acute pain set in. Then, too, as I mentioned, for the first time in my life I've been having some lower back muscle tightness and soreness for the past year. So I think the foundation for my problem has been under construction for some time. I believe that the cause is a combination of several years of TT training, lifelong bad posture, aging (I don't really believe that, but I'll throw it in for completeness), and the fact that for the past several months I've been spending more time at the computer (and hunched over, at that) than ever, marketing a book I have coming out. I've stopped lifting weights and I only ride every third day now, trying to give the healing process a chance.
I don't know about chiropractors. I really don't. I know people who swear they are helped by them, as I'm sure you do. Then I've heard stories about others that really make me suspicious of them. They probably range in competence from good to dangerous (like in all professions). If you're going to try one, I'd recommend going to one that's been talked up by some people you know (and believe). I also wouldn't let him take x-rays. They seem to be much too eager to take a bunch of x-rays. No x-rays are harmless. They should be saved for those times when the risk of the rays is overridden by the risk of not finding out exactly what the problem is.
Keep us posted.