I have had a lot of trouble with my sciatica since my 1st pregnancy and has gotten worse during this pregnancy. I had a massage which worked wonders for a few days but what has helped more has been not lifting DS or anything too heavy, not wearing high heels and trying not to stand for too long a period of time....sitting doesn't help either of course, lay down when you can. I still have problems with it but no where near as much as I used to.
HTH.....good luck with the rest of your pregnancy