painful shooting pain in my left foot, what that could be

Adel Sheikh Mussa

recently came back from a long period of injury staying away from running, I built slowly to reach where I was preinjury ( a damaged disk) started easy daily 5KM on treadmill, worked up to 10KM, but last week I developed a painful electric shock like piercing on my left foot not on my running time, but when I try to sleep, and it stopped from sleeping completely, this pain is changing sides but on the left foot, will appreciate if anyone experienced.