Can be sciatica.. Consult an orthopaedician or a physiotherapist. Physiotherapy will be very helpful and actually curative without any side effect.
Next Steps
Go to a physiotherapist.. Ultrasonic therapy +IFT +Heating therapy +traction (may require) +some strengthening exercises will +stretching exercises will be helpful for sure.
Health Tips
At home.. Rest +hot water fomentation +pain killer gel +no long sitting /standing /travelling /walking /driving +no cold exposure +no manual exertions +no weight lifting +avoid cold exposure +no stair climbing +no forward bending.