@Starkin,
There's nothing useful or productive to have non-medical people guessing what kind of condition you might have, if any. If it were me, I'd see a doctor ASAP. In the meanwhile, just be satisfied with normal jogging and put sprinting on a back burner until a doctor tells you that it's a benign...swelling or whatever.
You're body ïn its current state is not used to sprinting and sprinting is a high demand push on your body. Take it easy and be patient with your body and its progress towards getting into athletic shape. A law of physics says, "An object at rest, tends to stay at rest. But, an object in motion, tends to stay in motion."