What is this pain I'm having, a pinched nerve?

I’ve a shooting, tight pain down my hamstring that ends at a specific point in my feel. It feels tight, like a pinch, when I extend it in a certain way, and at a certain angle…sometimes so much so that it’s wince-inducing, really harsh pain.

Some backstory: I run and do yoga, quite a lot. However, the two seems to rub against each other in the wrong way at times—the running tightens me up, the yoga stretches me out. A while ago, I was overweight and had a bulged disk in my back, which may be a factor here.

In any case, this pain down my leg, which I imagine is a pinched nerve—I’ve felt it before, and rest and time took care of it. This time, it occurred after a long, hard run, followed the next day by a yoga session where my hammies were stretched and more agile than ever before….

Thank you! :)