Why does my left calf swell and cramp?

Calf Pain. This could be a serious problem. This is a symptom that can not be evaluated without seeing a physician. It may not be serious but needs to be seen.
Many causes. Without more information, difficult to say for sure. Could be related to your knee, problems with the musculature in your calf, or a vascular problem. Recommend you see a physician.
Leg cramp. Many possibilities Vein disease Knee issues Start with a venous Doppler sonogram it will identify vein reflux and may also identify a bakers cyst.