hello welcome to hcm well the location of your pain and the specific postures of the body in which you feel pain as described by you suggests that you might be suffering from a condition called as PIVD i.e prolapse inter-vertebral disc..there are protective cushion like structures present between the bones of our back,one disc is present between two vertebral bones i.e one above the disc and one below and this arrangement is present throughout the spinal region of the back....the function of these discs is that they act as SHOCK ABSORBERS for the back bones and prevents injury/dislocation/fractures of the vertebral bones .... when due to any reason,like a trauma or fall from height on a flat surface,the protective discs herniates out from its normal position,it causes compression of the surrounding nerves and spasm of the surrounding muscles of the back which in turn leads to a feeling of pain and stiffness....there may be only one prolapsed disc or else multiple discs may also get prolapsed depending upon the severity of the underlying cause.... first and foremost i would advice you to get a MRI OF LUMBO-SACRAL SPINE so as to know number and extent of the prolapsed discs,after you get your MRI you should visit with your reports to a orthopedician , he will evaluate your report and clinical condition by performing a physical examination and will prescribe you the most appropriate treatment necessary and instructions i hope you will find the above information to be very helpful take care hcm..