I Have Strong Tingling In My Right Leg And Foot

I have strong tingling in my right leg and foot that comes and goes at different times during the day. It is strong similar to the feeling one has when a hand or foot goes to sleep. I also have a lower back disc
problem I got a cortisone shot in this morning. It has really helped my back pain, but not the tingling which
is getting stronger and more often. I REALLY want to know what is causing the tingling.