What can cause tingling to your mouth, legs, and feet? I have been feeling a pain in the middle of my back to with some stiffness early in the morning

Not a whole lot..... ....will cause your symptoms in the MOUTH, legs, and feet all at once. Paresthesias can occur in and around the mouth during migraine heaaches but then, tingling and what not usually occurs in the fingers and toes...not generally lower extremities only. You need to be examined to see if the back pain ties to the feet. It for sure ain't gonna tie to the mouth. Good luck.