i began running again 3 months ago. and sicne the last 2 or 3 weeks i began feeling mild left knee pain. now the pain is pretty mild. like just couple of minutes it happen sometimes when i run and most of the time happens when i'm not running. The pain that i feel happen when i squat after sleeping i can feel the pain and after taking few steps not more than 5 or 6 steps after the squating the pain fades completely. that's pretty much what i've been feeling. i run 3 to 4 times a week for a distance of 2.5 miles each time. and most of the times my warming up period is like 10-15 mins. and i use professional running shoes. any help, or guidance?? thanks alot.