CALF:

Pain, one of the lesser-known dangers is deep vein thrombosis (DVT), a blood clot that can occur in the leg’s deep veins, and it can be life threatening. The danger is that a piece of the clot could break loose and cause pulmonary embolism [a clot in lungs]. Sometimes there’s just swelling without pain, if you have swelling and pain in your calf muscles, see a doctor immediately.

en-JOY!
https://triorigin.me/