Suggest Treatment For Abrasions On Skin After An Injury

On Christmas day I was stepping over a scooter and ran my calf down the kickstand. It frogged my muscle and i only had light abrasions on the skin. The knot in my muscle has been there ever since. It s about 30% smaller than a golf ball. It didn t hurt it was just slightly tender to poke. Two days ago the knot started twinging and slightly burning and looks very very lightly bruised. What could be the cause of this new symptom?