Can particular stretching exercises help treat sciatica?

Maybe: It is conventional to use exercises for the treatment of sciatica and a variety of back conditions. These exercises should be specifically tailored for your particular needs.

Yes: Specifically if some of your pain is coming from a common condition called piriformis syndrome.

Core Exercises: Typically core strengthening exercises are the best to help relieve pressure and forces in the spine. I would try and google some or look them up on youtube to see descriptions. If you can do them yourself, wonderful otherwise ask your doctor to get a referral to a good physical therapist for further assistance.