Any time you have swelling I'd see a doc or orthopedist and get some pictures taken unless you know you just bumped into a chair or something. Swelling can indicate a fracture, even a tiny one, and I'd think you'd want to know that before running on it again. Running is a very high impact activity, it don't know how quickly you got into it, it could be you're rushing the speed or the distance. But no way to know, and some people are just not suited to certain activities. Get it checked out by someone who knows so you can get back to what you want to do and don't cause a severe injury that will keep you sidelined for a long time.