First aid for sciatica?

Rest heat NSAIDs: Heat, rest (take pressure off back) and anti inflammatory medications such as Ibuprofen or naproxen. Stretch back muscles gently while supine doing pelvic tilts.

Sciatica: Meds, exercise, physical therapy including mckenzie centralization techniques, traction, inversion table. Many things are used.

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.