i had almost exactly the same experience. my pain was in the same area, l4-5, s1. i had rewached the point where i could only walk shor distances, very painfully, with a walker and was seriously considering a wheel chair. i talked to my dr (who is as much a friend as a dr) who referred me to a do who specializes in spines. bottem line, i had a laminectomy in 2002 and was vitrtually pain free for about a year. then the pain came back and kewpt getting worse. i went back to the surgio0n who suggested another operration to tske the screws out of the titanium rod holding my spine together. after this operation i could walk again without a cane for short distances and with a cane if i have to do walmart. i am also goinf to a pain management dr and am taking 3 percodet/day, 2 flexeril/day, and morphine for breakthrough pain (up to 3/day).
i'm not doing swimmingly, but it beats the devel out of the alternative. by the way, once you've had back surgery, no chiropracter will touch your back.
hope this helps.