Suggest Treatment For Herniation At L4-L5 Level Of Spine

I originally injured myself in 2008 which caused small herniations at L4 - L5 and S1 and did PT for approx 1 year and it did not help. Then I re-injured myself in the beginning of Dec. 2010 and have been doing PT along with two L5 injections and chiropractic adjustments.I am experiencing pins and needles in the buttocks and crotch area whenever I sit, along with left leg weakness which is more noticable when walking up the stairs, hills or uneven surfaces. My doc sent me for another MRI in February and wants me to do PT for another 3-4 months and get another injection. I haven't seen much improvement. My MRI says the following and I was wondering if these are the typical symptoms one would get and if there is a good possibility I need surgery1) multilevel degenerative disc desiccation and degenerative facet disease 2) L4-5 central and bilateral paracentral disc protrusion causing minimal 8.7 mm central canal stenosis and potentially bilateral L5 nerve root origin compromis which has increased in severity compared to mri of Feb. 2010. 3) L4-L5 moderate bilateral neural foramen and lateral recess stenosis which also increased in severity and 4) L5 - S1 left paracentral disc protrusion without nerve root compromise or central canal stenosis. Any suggestions or is surgery in the near futrure. Thanks!