Woke up yesterday morning with pain in back of left calf, almost where my knee bends. No swelling/redness. Deep vein thrombosis?

Leg Pain. Not likely unless you have been sedentary for prolonged period (e.g. Traveling); have had previous blood clots; or have cancer, recent trauma or surgery, all of which are typical risk factors for leg venous clots.
Calf pain. Any injury? Did you do any strenous work or run day before it start? If no trauma, no strenous activity, no swelling or rash then try ice for day or two. If it is constant then get evaluated.