How Can Pain In The Lower Back And Legs Be Treated?

I know I have two herniated disc at the L4 and L5. My pain largely remained in my low back. Back in July after driving around for 8 hours shopping, I got out of the car and the pain was horrible both in my back and my left leg. I was barley moving and remained on ice packs for 3 days and it was another 2 weeks before the pain was manageable. Now, although my back feels weak and the lowest part of my back is tender “like a bruised muscle”, the severe pain has went to my left leg especially while standing or attempting to walk. When I push through the pain, burning, and muscle soreness and numbness gets worse. When I rest afterwards I experience muscle spasms from my left butttocks. I cannot lie down in a prone position without extreme pain from the same area as The spasms . After things calm down I can lay in the prone position, but as I rise the pain and burning start in my leg again. Flexing at the waist backwards and sometime forwards will send sharp pains back into the buttocks area? Why did the majority of the pain shift from my back to my leg? Or is something else causing the pain in my leg and buttock? Will I require surgery?