I know you have been examined for DVT but do not exclude the possibility of a blood clot(s) the pain is now an indicator. Have you received any recent trauma to the foot, ankle or lower leg recently? A couple of years ago I reported an injury (on this Forum) sustained when a car ran over my foot - and I banged the ankle against a footrest (I was on a motorcycle of course). Your symptoms are more and more similar - like you, my foot, ankle and lower leg ballooned with severe pain extending to the knee. My clots were - one in the groin and two in the crease under the knee joint.