What Causes A Sharp Stinging Pain In The Calf Muscle?

I get a stinging sensation on the front of my calf like as if I have been bitten by a wasp and then I get a perfect round red hot swollen spot the size of a fifty cent piece. Stays for about two weeks and then when it is no longer red it stays in a round brownish colored spot. It reoccurs periodically again with a sharp sting and then the raised red area again. I have had this four times in the last year.