I Had Arthroscopic Surgery On My Right Knee. I Have

I had arthroscopic surgery on my right knee. I have a bakers cyst that they were unable to remove. After surgery I was told that I needed knee replacement but they cleaned it up the best they could. 1 week post op I went in to have my stitches removed and they aspirated my bakers cyst. My knee was the only thing that was swollen and was continuing to have less swelling. 4 weeks post op I went back to have the cyst aspirated again because I was going out of town. After our flight and while on vacation my leg from below my knee to my foot was very swollen and it felt like my calf had a cramp in it. I went back to the Dr when I returned and he sent me for an ultrasound to rule out a blood clot. He told me that if I didn't have a blood clot I just need to start physical therapy. I don't feel like I can do PT. My leg continues to stay swollen below the knee, my calf feels very tight with a cramp. What could this be?