Oh yes, i have had the displeasure of very bad sciatica when overweight, it actually prompted me to go optifast about 18 months ago to lose weight and yes noticed major improvement as i lost weight (sadly could not keep weight off, hence being sleeved monday). I also had physio and that helped immensely. I never took any pain killers, allergic to codeine, can't take anti inflammatories. I did also have a cortisone injection, that was really my turning point, it has to be don under ct can and does hurt like a bitch but it enables you to participate in physio by decreasing the pain. Also make sure you keep moving, not running marathons or anything but spending all day on the couch or in bed will just cause you to stiffen and seize up. Heat packs can help also. I suggest going to your gp to discuss cortisone injection or other possible treatments.
Good luck, hope it starts to feel better soon :)