Pain in Calf Muscle and Arch of Foot?

[Giggles-for-life]

Today I noticed a pinching-like pain in the back of my calf, and also in the arch of my foot on the same side (left). It hurts to walk, and hurts whenever I straighten my leg especially. What can I do for this, and what could be causing it? Should I be worried? I have not exercised recently, so I couldn't have pulled something. In fact I have been very sedentary lately.

Thanks for your help.