<s>[INST] Behind my knee on my left leg only, I've had some what looks like veins pop.  They look like bruises but they're not.  I also have a small knot about the size of a pea in the upper part of my left thigh.  The area behind my knee almost feels like the circulation is cut off. [/INST] Hi, you could be having Varicose veins or Bakers cyst or very unlikely but possible to have an Aneurysm of the Popliteal artery. You should get an ultrasound or a Color Doppler of the area done to confirm the diagnosis and then treatment can be guided accordingly. Take care. </s>