Sounds like you might have torn (at least partially) the Achilles tendon which is a big band the attaches the calf muscles to the heel bone. For an achilles tendon tear, I reccomend heel lift inserts or a 1 inch heeled shoe to ease the tension on the tendon. Ice and cross friction massage (rub across the sore area) are both excellent ways to reduce pain in a tendon.
Without examining you, I cannot be sure. So, a sports medicine specialist would be a good choice for a second opinion because Achilles Tendon tears are very common.
Dr. Christina Lasich, MD