How To Treat Left Buttock, Leg And Foot Pain

I am suffering with sciatica at the moment following a fall just before Xmas. At the end of Sept I had surgery for a meningioma (5cm) and am recovering from that - could really do without the back pain as well!- tho actually the pain is mostly in left buttock ,left leg and foot. Any suggestions where I go from here - my GP prescribed Gabapentin -300mg 3 x day but the pain is still considerable. I also take paracetamol and ibuprofen , use ice and heat packs and do gentle Pilates exercises but am in agony much of the time .