Lynda, sorry about the awful sciatica pain. Sometimes ice will help with nerve pain. Have you talked to your doctor as well as with your chiropractor? Imaging might be needed to determine if the sciatic nerve is being compressed or inflamed due to bone spurs, a disc problem, or spinal stenosis (narrowing). Getting a prescription for physical therapy may be better/safer than trying some exercises you found online. Also, steroid shots can help with spinal nerve pain. If your sciatica is due to muscle spasm rather than to spine issues, checking your electrolytes might be helpful. You could be short on Magnesium or ? And of course your doctor can prescribe muscle relaxants to give you relief and hopefully help turn things around.
In short (LOL) -- this has gone on long enough, and it's getting worse. Get thee to the doctor!