Hi Margaret
Sorry to hear about your sciatica, I had a small attack a few weeks ago which was mild by comparison so I can sympathise. You really need to do some piriforma stretches if you can manage - if you google them it will bring up plenty but the one I did was fairly easy so I'll try and describe it here - give it a try, it does help. Lie on the floor on your back, bend your knees keeping the feet on the floor. Lift one leg and cross it over the other bent knee (so your foot is resting on the knee) - this will stretch the muscle. If you can do it it's even better if you can slightly lift the leg(keeping that leg bent) that is still on the floor, increasing the stretch. Do it for as long as you can as often as you can - you'll hopefully be amazed by the results.