Tendonitis

Tendonitis is inflammation of a tendon. The most famous of these in the lower leg is Achilles tendonitis. The tendon becomes inflamed and sometimes swollen, sore to touch and sore to do activity. Overuse or overstrain of the muscle can be a contributing factor here. Poor mechanics can lead to the overactivity of a muscle and the tendon for that muscle pulls to hard where it inserts and then becomes inflamed.

Rest really helps this and icing the area can reduce the swelling. But of course if you are active you want to get back to your activity.