Back pain diagnosed with Spondololythesis Grade 1 in L5-S1?

A 25 yr gym freak, I started jogging after a while on a hilly terrain. Gradually, I started feeling pain in my lower back. It was a strange kind of pain which was only when I made some specific movements, and it extended like some nerve was pinched.I continued playing before and ignored the warning signs. After 2 weeks I was doing ab crunches lying on ground, when I started feeling a pain that was unusual. I checked out with the doctor the following day and got an X ray done. report came, it said spondololythesis in L 5- S1 grade 1.He advised me to take rest. I hadconstant pain (it was a dull pain, bearable on the left side of my lower back). I was very precautionary of whatever I was doing.But after 2 weeks,went for cycling and the next day I went for a climb up the hill, I came back and I felt a terrible pain along that bone. I took 4-5 pain killers for the next 3 days and the pain went away. The dull pain continued. next 10 days I didnt do nethn and pain went. But it comes back,