I am 27 years old, IT professional. After sitting on a chair at usual sitting posture for about 1 hour or so, when i get up, i feel pain on my popliteal fossa of my left leg (lower side of knee joint area). pain takes around 30 seconds to go away. afterwards leg feels completely normal. same happens when i travel in bus or car. when i suddenly get up i have this strong sensation of pain in that area which last for very less time. I weigh 80kg and height is 174cms.