Sciatica is pain the lower back, that runs into the buttocks and leg. It is caused by something pressing on the sciatic nerve in the spine (usually because of a problem with one of the vertebrae).
The pain will probably go away after a few days if you rest. But if you don't take care of the problem that caused it then you will have another (usually more severe) attack.
If you're suffering from sciatica (you have my sympathies) then you should consult an orthoped as soon as you can. Some back problems can be solved by doing some exercises (especially if you catch them in the beginning stages), but a more severe problem may need surgery.
