If its a lymph node that is soft and movable, and its causing some pain, its likely responding to an infection. That's what they do. It would be a lot harder if it was something worrysome.
It might also be a muscle or a lot of other things. I couldn't say for sure. But I do know one thing: If you keep jabbing at it, its gonna keep hurting, no matter what it is. That's definitely gonna cause swelling and pain.