I had a pain in my chest that happened after increasing my exercise levels, and it stayed around, first discomfort, then acute.
Turns out I had a nodule on my lungs that had ruptured, leaking air into my pericardial sack, and putting pressure on my heart. It stayed around for a week, and the doctors were very worried when the first x-ray came back. Apparently it was a small nodule and healed quickly, and the bursting may not have had anything to do with my activity level, but exercise and hard breathing pushed more air into places it shouldn't have been. Three weeks of rest and another x-ray to be sure the air was all gone, and lingering pain while jogging after that. If it had been bad they'd have had to put a big needle in to let the air out.

Just go get it checked out - you never know what's going on in your own body as well as people who are trained and have the tools to look inside of you.