How Can Foot, Ankle And Calf Swelling With Pain Be Treated?

My left foot was mildly swollen this morning right after getting out of bed. When I got home after work (desk job), it was really bad and swelling has spread to ankle and half way up my calf. Also the right foot/ankle is just a little swollen. the left one hurts alot from it being so tight. I am 38, female, 300 pounds. But have had NO trouble like this before. I have no other medical conditions that I am aware of.