Hi when ever you're lifting any weight there is sudden compression force on your back if your back muscles are weak or your posture is not good while lifting weights there will be pain in your back which gradually can radiat to one or both legs.
You try some back and core strengthening exercises for 8 weeks. Until that time try to avoid heavyweight lifting and forward bending.
If problem still persist than consult nearby physiotherapist
for proper examination of your back.