Past several months my lower back, spine, seems to "go out" when my menstral period starts. Only last for two or so days, but I can't really even stand upright. Should I be concerned, what is the cause, what can I do to eleviate pain.

Sounds like your one of the unlucky to have severe cramping before/during/after periods, I've had friends mums who had it so bad they were sent to the hospital just because it got so painful ):
You should check with your doctor to be sure it's just that and to see if they have any suggestions on how to help with the pain? I assume they might prescribe painkillers if it's that bad but you can always ask if they have herbal options some docs remain up to date on it!
I say see your doc only because you imply that it's a new thing, if something changes with your body and how you know it regularly functions it's always good to check...
I doubt my cramps get as bad as yours though I have had them bad enough that I didn't want to stand upright so I know that feeling... usually a hot bath can help me, maybe try it out if your time allows?
Good luck