Swollen painful right leg

38f, high bp, anxiety, histoplasmosis of the lungs all being treated with medication for about 2 years +. 1 month ago my calf muscle felt really tight and painful. Took ibuprofen and went on a long walk, within a day the pain subsides. My thought was unstretched muscles (work an office desk job) and/or dehydration. 2 weeks ago, it started again, then pain moved into the back of my knee and halfway up my thigh. The pain hasn't been as bad the last few days after taking another long walk on Sunday. When I got home last night the leg was so swollen it split the back of my compression socks. I slept in the recliner with pillows under leg and got the swelling down about halfway. Once I started moving around and to work today, it's swollen again. I still have a constant ache behind my knee and calf. Feels best when walking, but also makes me short of breath because my leg feels so "heavy." I know I should see somebody, is it worth going to urgent care or ER right away?