Sounds like an overuse injury
Like paul and crazybuddha said, resting for a few days will help. A few years ago I re-started a running program, tried to do 2 miles at once, and almost immediately started having knee pain very similar to what you describe. The orthopedist diagnosed bursitis. Treatment was ibuprofen, rest and elevation for 3 days, then 1 week's rest. Then I had to restart the exercise program slowly, build up to 2 miles over a couple of months' time.
And shoes, like Cyborg says. Invest in a good pair of running shoes (not cross-trainers) with good cushioning and a stable base. They'll help prevent shinsplints, too.
There is a great streak of violence in every human being. If it is not channeled and understood, it will break out in war or in madness. ~Sam Peckinpah