Hey there!.
How painful can sciatica be!! I am 25 yrs old and experienced sciatica for the first time about 3 yrs ago. Visiting the doctor can never hurt and is always a good idea, however with my situation I found the doctor told me what I already knew, and could not offer me any relief besides:

PHYSICAL THERAPY - which we all know is costly, and time consuming.
PAIN MEDICATION - which is definetely ONLY a short term solution, but is really just a band- aid, being that the problem is never actually fixed.

If you have the patience stretches and exercise is really the only solution!!. There is one exercise which my partner suggested to me - after having done a manual handling induction at his work site which I truely sware by!. When he told me the exercise I was like.. yeah right as if its going to work, I mean how can something so simple help something this painful!! but anyway I tried it and voila!

EXERCISE
- stand comfortably/ naturally with your legs about shoulder width apart
- position your hands comfortably on the small of your back (ensure that thumbs on the
stomach side or fwd, fingers placed on your back - just picture the way a pregnant lady
holds her back!)
- Using your hands as support, gently stretch your stomach fwd in a stretched motion
- hold this for 10 seconds, and repeat 8 - 10 x

This sound ridiculous I know, but it was a godsend for me, I teamed it with the stretch which was mentioned earlier.

EXERCISE
- Lie flat on the floor
- bring your knees to your chest
- hold your legs there for about 10 seconds to feel the stretch

If you do these you should feel better by the end of the day, persistence will have you feeling excellent within about 1 week!!
Goodluck!