I had done some moving furniture & stuff a few days prior, so I didn't experience any pain before (probably because I had been stretching), but it just crept over me. I don't really self-medicate, but I figured it would help in the meantime while I got a massage, to speed up the process so I could go back to normal... I react well with Valium, but that's not what I had on me, so I kind of improvised.
So, it didn't have anything to do with my usual pain. Or else I would have treated it differently or just dealt with it.

When I find a doctor, I'll ask what was up with that reaction. I mean MAYBE there were muscles or connective tissues that were stiff but unnoticeable until the medicine kicked in? That's the most that I can deduce on my own.

Yeah, I do most of the alternative things you mentioned. Stretching pretty much daily as a preventative, hot showers, icy hot... I want to buy a TENS though. And I'l have to read up on arnica to see if there are any contraindications!

I just posted in this forum because I figured that other people with chronic pain MUST have had bad reactions to certain meds... And since I don't really get much muscle pain & google searched everything, I thought I'd ask. : )

I got an ulcer from taking too much Advil from my arthritis. But since I now know that Valium can be used at a low dose for muscle tension (I've usually only had it for anxiety), I have a safer option should any circumstance arise again!

Thank you muchly