I am 26 years old and am having pain in the back of my right knee and down my leg. I am 5'8" and 205 lbs. It started a few weeks ago it felt like cold chills running up and down my leg below my right knee and would hurt occasionally. The veins behind my knee look purple and bulge slightly. In the past week it has started hurting behind the knee and on down my leg into my foot while I am standing or walking. Normally it doesn't hurt while sitting unless there is pressure on the back of my knee from the chair and it doesn't always hurt then. I had a c-section 11 months ago and I smoke. I am just wondering if this is something serious that I need to go to a Doctor for or if it is something I can put off until I have insurance? Thanks.