Talk to General Physician on Pain In Buttock And Backside Of Both Thigs

My cousin felt pain in lowerback but after some exercises at home he had no complain for back pain. But since last month he felt pain in backside of both thighs so he went for MRI. And that L4-L5-S1 buldge is diagnosed which is main cause of pain in butts and thighs, the most of pain is in sitting position, though he has v minor pain in back which is ignorable. Want to know what exercises he should start EITHER FLEXION OR EXTENSION. Reports and images are attached.