The left outside part of my shin/calf has been bothering me lately. Don't recall anything that injured it. Hurts most when crossing my leg. What could this be?

Possibly sciatica. There are a number of potential causes and I would not hesitate to be seen. One of the more common causes is a sciatica, which is an irritation of a nerve in the back that can cause pain that runs down the thigh and leg.
Dysesthesia. This discomfort unaccompanied by redness or history of injury, May be due to an irritability/inflammation of the superficial nerves in that part of the leg or nerve entrapment of a nerve or nerve root causing referred pain at the side of that lower leg. Phlebitis of a calf vein appears less likely. If symptoms persist, see your physician for evaluation and advice.? referral to a neurologist, also.