When i manipulate, massage, rub up against may medial tibia nerve i get a numbing shock from the area just below calf muscle through to my toes.

Irritated?: I would suggest that you seek medical evaluation as the nerve might be pinched. If that is the case it might get worse with time.

Think tarsal tunnel: Tarsal tunnel is a condition of of the tibial nerve on near the inside of the ankle. Think of it as like carpal tunnel, but at the ankle instead of the wrist. You can experience, shooting/tingling pain, numbness, weakness and other symptoms around the ankle, and it can radiate into the heel, arch and even toes. Some radiation into the calf is not unusual. See a podiatrist for care options.