As per your history you are a mild hypertensive well under control with drugs. You are not diabetic, otherwise a healthy opt weighing 63 old man doing your routine work. You have pain in the left side hip ?radiating to the left lower limb up to foot both in sitting and lying posture but very severe in left turned lying posture. All these go in favor of some problem in the lumbar spines or lumbo sacral joint.
It may be SCIATICA
or some problem in the lumbar spines or discs compressing the nerves.MRI
of lumbar spines including lumbo sacral joint and sacral bone will clearly indicate the cause of the pain. Sometime evaluation of whole spinal cord
may be needed. If it is normal nothing to worry. Consult a neuro surgeon. Till then lying flat facing up without pillow and avoiding jerk like movement which occurs during two wheel drive to be avoided.