Diagnosed With Sciatica Pain In My Right Leg From Pelvis

Diagnosed with Sciatica pain in my right leg from pelvis down to the knee. I am taking Relaxon a muscle relaxant, Diclofenac Sodium, Neurobion tablets and Quetiapine Tablets ( before going to BED, for the last 8 days. Except for the initial relief from burning pain my knee, the pain continues. The pain is in the right thai, knee as well as in the right hip. I can not sleep lying down. I sleep in semi sitting position. I want to know the best posture that should help reduce pain and help improve my condition. Any advice Thanks