Try and figure out whether it is bone, muscle or tendon.

Is it the upper calf? Can you flex your calf hard without it hurting?

Play around with your knee cap and under it. Does it hurt?

Press on the bones, is there pain?

Basically, have a good poke around and find exactly where the pain is coming from, what sort of pain it is etc. The more specific you are, the more we can help and the less time you will eventually spend at the doctors.