I can't offer any potential remedy I'm afraid, though but I'd guess the numbness/pins & needles is being caused by excessive pressure on the foot where there shouldn't be... The point where this pressure is though... you'd need to ask a doc/physio about.
Not too long ago I was finding the left side of the tip of my right big toe was going completely numb on runs, and it turned out to be pressure on the left hand side of the ball of the foot. I relaced my trainers so they weren't so tight and it seems to have fixed it

Sadly I'm not too sure what to suggest if your trainers are already fitting well
