Lower back pain, lumbago. Serious?

Hi, I'm having pain in the lower back and buttocks and from today I've also started having pain in the tail bone which is very uncomfortable. I'm not able to sleep on the back or the side comfortably due to the pain. I've had full spine x ray done, ap/l, to be normal, only comment which concerned me was that the spine has lost it's curvature, I've seen an orthopedic who said it's severe muscle spasm and advised complete bed rest, I've been prescribed acenac p, gabantin 100 and rablet 20, I need a second opinion. The doctor has thoroughly checked me, there was no pain or numbness in the legs or in the upper back, just pain in the lower back. But from today the pain has started with the tail bone. What concerns me is that my lower back seems to me to be completely flat and due to the tail bone has started paining. Will it be fine? Or is it something serious? My email id xxxxxxxxx@gmail.com