I had a similar problem last summer. It is likely from working a little too hard. Have you been doing other activities besides cycling? Just ice it down and get some Icy Hot or other pain relieving cream. When I got it I assumed it was tendonitis and got a neoprene calf sleeve to wear on it when I was working out. It helps to keep it warm. Ultimately you need to lighten up a bit and give it time to heal.