Hi Hope this message finds you in good health. I have gone through your complaints and understand your concern. I generally see many cases like this at my clinic.I give them a splint,rest,analgesics,anti-inflammatory tablets and ice pack till the swelling reduces to some extent. Then i get an xray and if necessary an mri done to find out the extent of injury. In your case,there are 3 possibilities- POSSIBILITY 1. nerve inflammation- there may be no bony involvement,only the soft tissues around the back might have been strained. POSSIBILITY 2. muscle cramps- due to weight gain your legs have been put under extra stress that may cause muscles to cramp and cause continuois pain POSSIBILITY 3. lumbar disc prolapse-U seem to have compressed a nerve in the back somewhere that might be causing radiating pain in those regions.Possibility of a lumbar disc prolapse should be kept in mind. I suggest you get an Xray as well as an MRI to find out the exact cause. Physiotherapy,analgesics,anti-inflammatory drugs should help. Avoid surgery as far as possible. But i assure one thing, even if it is either of the above 3,all have a good prognosis and you should eventually get back to normal in coming few days.Nothing to worry about.Do get back to me after ur mri reports are ready. I hope your question has been answered. If you have any follow-up queries,feel free to consult me anytime. Thanks,Take care,God bless.