Hi and welcome to Healthcaremagic. I understand your concerns and I will try to help you as much as I can. Yes, it may be burst Baker cyst and in this case it should be treated with painkilers and cold compresses. However, it may be deep vein thrombosis or so called DVT although this is not very likely. It means that clot is formed inside the big leg vessel. So you need to do Doppler ultrasound to rule this. Vein thrombosis which is manifested with unilateral swelling of the leg, pain in calf and lividity of the skin. Some conditions such as pregnancy, obesity and recent surgery may increase the risk of it. This may be serious if blood clot travels to heart and lungs so it should be ruled out as soon as possible and then appropriate treatment can be started. In most cases it include strict resting heparin infusions and aspirin. More invasive procedures are rarely required. I hope I have answered you query. If you have any further questions you can contact us in every time. Kindly regards. Wish you a good health.