Knee Pain

Recently I have started getting pain just above and behind my knees

I mountain bike a lot and do 2 personal training sessions a week where the focus is on legs. It isn't unbearable just hurts a bit when I squat down to pick something up, sit on a chair or toilet etc. I have been grinding my gears in my bike a bit, so I thought I will spin for a while until my knees dont hurt. I just wanted opinions on whether I should keep exercising and buy a foam roller as well as paying more attention to stretching or whether I should go to a physio about it?