I have been experiencing leg pain, soreness and stiffness in my right calf for about a week closer to 2 weeks. It began after taking my annual flu shot as soreness in the bend of the leg, then stopped. After a few more days the calf began to get sore and unable to stretch as much as usual. Now it s begun to swell and has pain when I put pressure on it or walk most of the time. It gets worst after sitting too long. What are the possible causes?