Severe pain in back of left knee, generating down to calf, or upper thigh, swelling in calf and downward to ankle and foot. Can barely walk on it, I do put it up on pillows when sitting or laying down, but as soon as I am back up on it, severe pain begins. Did have X-ray said arthritis in knee, did have ultra sound no blood clot, but did not give me any direction of what it is, or what to do for it. To take pain pills for it.