Have been a runner on and off for years, recently started weight training at the gym (6 months or so) and dialled back the running for a while. Picked it up again and I keep getting pain a couple of inches above one knee - feels like a bad bruise every time I bend the knee. It lasts for a few days and then eases off. I'm not going particularly far or fast - 5 or 6 miles max, mostly less. Have never had anything like this before and I don't know what's causing it or what to do about it! I really don't want to have to give up running as I love it. Help please!