Heel of golf club is striking ground as I am making contact with ball causing a week shot with lost distance?

This year I am having trouble hitting my 7 Iron thru Pitching Wedge, I seem to be striking the heel of the club just as I am making contact with the ball, result loss of distance, this happens no matter what, on the tee of a par 3 or off the ground on 2nd shot and idea on what I maybe doing wrong