Twelve to thirteen years? Have you seen a neurologist? Sciatica in itself isn't a "condition" but a sign/symptom of a condition. The most common cause is the sciatic nerve root being compressed by the herniation, rupture or enlargement of lumbar spinal discs.
Just a suggestion but if you have been having sciatic pain that long you might consider seeing a specialist and getting an MRI.
I have daily sciatic pain myself so I know how painful it can be. I've had surgery once and two failed epi-dural steroid injection procedures. I'm supposed to have a second discectomy or spinal fusion depending the damage but I can't afford it

. Regardless I just wanted to suggest a visit with a neurologist who may be able to suggest a treatment which may be as simple as some basic massage therapy.