I have herniated disc on L4 L5 and buldge on L5 s1. Before pain in flexion now more on extension. Y? Any sugstn? Mri done

Many treatments. Start with physical therapy and core conditioning. At some point an epidural steroid injection might be helpful. If all else fails and your symptoms impact your activities of daily living, surgery can be curative. I would suggest seeing a spine surgeon with expertise in minimally invasive spine surgery if it comes to that.
Flexion pain to ext. Herniated disk will likely cause increased pain with flexion. This motion will increase disk pressure, and cause the disk to extrude more and irritate the nerve causing shooting pain. On the contrary, extension usually reduces disk pain but then causes pressure on the facet joints. Any pressure within the neural foramen will be made worse by extension. Initial treatment is pt for both.