Last Wednesday I finished up my squats and felt pain in my groin area. I haven't lifted since and now I have a dull ache when not moving, but if I rotate my knee out, away from my body the pain becomes quite sharp. It's my left leg and when I rotate the knee out to 11 o'clock the pain builds and peaks right at 9 o'clock. and gets better once it gets closer to me and I have no pain if I were to rotate it inward to 3 o'clock.

The area which hurts is right in the crease from by my leg and my torso, just bellow where the quad tendon crosses the joint.

How in the world do I determine if this is a muscle belly injury or a case of an injured tendon?