Since I refuse to take any more narcotic painkillers or steroids, I really don't have much to offer to ease sciatic pain from a medical point of view. I have found gentle stretching can help relieve some pressure. Make sure you do not eat anything that will cause a flare-up of inflammation. For me that is simple sugars, bread and corn. (I love corn, but no longer eat it because it causes so much inflammation) Gentle inversion can help relieve sciatic pain stemming from pressure on the nerve from a bad disk. I have an inversion table, but just a piece of strong plywood set up at a 25-30 degree angle can bring a lot of relief. It is also important to make sure the liver and bowels are both working well. The nerve meridian run along the same track and a congested liver or colon can aggrevate pain along the sciatic route (this is according to my chiropractor). Hot and cold therapy also can bring relief. You can alternate hot and cold pack on just the lower back, or use heat on the back and cold on the affected leg and then reverse the packs.
Can you get the herb turmeric? It has strong anti-inflammatory properties, some writers have compared its effectiveness to presnesone. I can buy it in capsules, but I have also bought the powdered turmeric and made my own capsules. Since it is also a primary ingredient in curry, eating curried foods can also help. Ginger also has anti-inflammatory properties, but is not as strong as the turmeric.
You can get temporary relief from over-the-counter NSAIDS like Ibuprofen, but avoid taking too much as it can be hard on the liver and stomach.