HI! So for the last couple of days, I've been having some soreness in my left foot, and then yesterday it went up my leg and now I have a pain behind my knee and in my calf area. I looked after work today and theres a swollen part coming from behind my knee to kind of the side of the top of the calf...probably 3 inches long. It's not discolored, just a lump that i noticed. I am overweight (very) and I work at a job which keeps me on my feet about 30 hours a week. I'm 21, and have recently started exercising and running on the treadmill, but I haven't gone on the treadmill in a couple of days, so I don't know if this is the reason or not. I'm worried about it, and I wanted to know if you knew what it could be and if I should go to a doctor. Thanks Heather