Pain in side of leg and calf

I am 51 and have had on going lower back pain to the left side around my belt line for 15+ years.  The other day I woke up, bent over and felt a sharp pain in that same area.  As the day went on the pain went in to my left hip, the side of my thigh and then down in to the side of my calf.  I had trouble rolling over in bed and was not able to sleep at night because of the pain.  The pain is starting to subside but it has not gone away.  It has been 3 weeks since the initial pain onset.  I had an MRI three years ago that showed bulging discs on between L4, L5 and S1.  Is the pain from a pinched nerve in my spine or sacroiliac?  

[stillstruggling]

I know what you are going thru, i have the same pain mostly on the left side but also on the right side. I finaly got in to see a pain managment Dr who does facet joint injections, it took 3 or 4 oppointments with him to find the right joints but when he did, it got rid of my leg pain.  I had nerve ablations at L1 to L3 facet joints and the relief lasts about 12 months, i also have had the left SI joint done to get rid of the pain in my butt and across the lower back.