Re: Knee hurting after running.
I was plagued with a knee problem a few of years ago. Simply down to running too much and doing too much high impact training.
I have reduced the miles and now focus more on being faster at the shorter 5-10K distances instead of running half marathons.
I now always run with a knee support which seems to prevent the injury returning. But I don't put in anywhere near enough miles as I used to. Hell my long run 4 years ago was longer than my total weekly mileage now.
My advice is to get plenty of rest, even after the pain has gone give it a few weeks before running again and start of slowly and build back up to your previous mileage. Also get a knee support and wear it every time you run.