I was given stretching exercises by my physiotherapist for sciatica. If you look on you tube there are lots of gentle exercises which definitely help.
One of them is lying on your back and bending the knee up towards chest as far as you can without hurting yourself, then gently pull the leg towards chest and hold it for 10 seconds, repeat 10 times if you can. Do this twice a day.
The other was to sit on floor and cross the affected leg over the other and try to put youf foot on the outside of the unaffected knee and gently pull and hold, this should stretch the outside of the affected thigh.
Not sure if I explained that very well but stretching exercises help a great deal.
WJ