Hi, recently been running again and did 10k the other day. Since then my right knee has been painful and feels week, specially when I walk downhill? I just went jogging again and had to stop! When I bend my knee a watery lump sticks out the right side, about half way just below my knee cap?! It feels like water build up a bit, looks like a huge varacus vein! The pain shoots around the back of my knee? Any ideas? Really want to keep fitness plan going!