Injury

I've recently begun running several times a week. During a 5-mile run the other day, I began experiencing pain in my left knee. Specifically, it feels a bit like a bad bruise below the kneecap on the inside of the leg, and the pain has continued for several days - especially when sitting for long periods of time, or even while walking. I want to keep running as I'm training for my first half marathon, but I don't want to further damage the knee if running will make the problem worse.

Has anyone had this experience? Am I ok to keep running through the pain? Are there treatments (brace, exercises, etc.) I can try to reduce or eliminate the problem?

One of my friends just hurt his his knee wakeboarding this morning. He is from out of state and here for a wakeboarding competition this upcoming week. He is not sure what he did to it but would like to see a doctor or urgent care facility today (Saturday) to see what is wrong. He says there is pain when he walks and out to much pressure on it. Does not have full range of motion.
Any recommendations on where he can go?