Swollen quad above knee

I have been w/o for about 3 weeks my left leg above my knee is swollen. On the outside of quad about 4 cm above and to the outside of knee is a lump its like right at the bottom of the muscle the inside is sore too and looking at both knees can easily spot the difference

At first u thought it was just normal muscle pain from growth but it still hurts after a week. When I do leg presses or squats it doesn't hurt. It also feels stiff when I fully bend it.

Any ideas anyone it doesn't seem to affect me to much strength wise just feels very stiff all the time

Also when I straiten out my leg you get that bump above knee were quad joins knee on my sore leg this lump is twice as big as other leg