Most back pain goes away on its own within 6 weeks. Walking is good for most back isssues. You could take ibuprofen.
Do you have any history of back injury even something that you may have brushed off as minor or been involved in sports/gymnastics/chearleading? I have those same symptoms; however, mine are specifically from back problems i.e. herniated discs, degenerative discs disease, etc. If it is your back, please seek treatment immediately!!
See your doctor. You could have a pinched nerve or slipped disc.
I agree with JMD_RN. It could be sciatica from a pinched nerve. I get it from time to time. You need an orthopedist. Hope you are able to resolve your problem.