Replying to Doctor NS, I have terrible heel pain

Title says it. It happens sometimes, only after I do alot of running, mainly in the gym. I was recently running in the gym for around 5 or 6 hours (school wake-a-thon) and soon after I got a really bad pain in my right heel that hasn't gone away yet, I've had it since Friday night. It got a little bit bettter, but got really bad again today after gym. It's only my right heel. Just an intense pain around the back, really hurts when I walk, and also when I touch it. Any advice NS?