At the end of last year I did a field exercise filling in as a rifleman on the TA commisioning course Module 3 FTX, fairly hectic inf type stuff. About halfway through I developed back/neck pain which the CMT put down to just requiring stretches to clear it out. Since then I seem to be susceptable to lower neck/upper back pain when in prone firing position for more than a few mins. I was on an FTX this weekend in sigs role so not much weight being thrown around for a very long time, but a while was spent prone and I am still feeling back pain in a fairly similar manner, though a bit duller, even two days later. Is it likely that it is just cramp/needs exercising or is my spine about to fall out? I'll probably wander over to a doc if it lasts much longer. Any recomended exercises/stretches to build it up better and avoid in the future?