"Sciatica (or sciatic neuritis)[1] is a set of symptoms including pain that may be caused by general compression and/or irritation of one of five spinal nerve roots that give rise to each sciatic nerve, or by compression or irritation of the left or right or both sciatic nerves. The pain is felt in the lower back, buttock, and/or various parts of the leg and foot. In addition to pain, which is sometimes severe, there may be numbness, muscular weakness, pins and needles or tingling and difficulty in moving or controlling the leg. Typically, the symptoms are only felt on one side of the body."
Have you been officially diagnosed with sciatica, or do you assume you have it based on symptoms?
I myself have saccroiliitis and spinodyliisis so I know a thing or too about lower back pain.
The best thing you can do is lift weights. Your body releases anti-inflamatories after a grueling workout, and actually causes inflamation during your workout. Part of getting big I suppose.
Start off with a regular squat and an empty bar. Ensure you use 100% strict form in 'slow' and controlled movement. Concentrate on your abdominal muscles while performing the exercise, as your main goal is to strengthen the abs while performing a movement which will likely cause sciatica to flare in your day-to-day life.
This way you strengthen the surrounding muscles in a functional way, which will allow you to take the weight off your spine.
I know arthritis is different, but doing DL's, squats and even chins while maintaining my focus on my core, and keeping it tight, has done wonders for my back- AND ABS.