What Could Sudden Swelling In Only Side Of Body Indicate?

Hello, I have had this problem recently with swelling on just one side of my body. Mainly on my left side from the hip down. I have had edema before when I weighed almost 400 lbs. I had WLS and now about 190. I used to take a fluid pill. I have not had to take any for over 6 years. This swelling is very odd. I have never had swelling in my thigh before... it starts there......and then goes down to my feet. I have never seen it swell like this before. After it goes away.... the top of my foot is very sore...... from where it was swollen so badly. I take care of it by putting my feet up while I sleep. I have not started any new medications.. or started eating anything different. It gets so bad.... I have to actually pick up my leg to get into a car. It feels like I am dragging a stump when walking. I have made a couple appointment s with my family Dr to see this......but by the time I get in.... the swelling is gone. I did ask for a fluid pill to take care of this but was told he did not want to RX me anything in case its a blood clot in my leg. I have not injured it...or hit it on something. I am a disabled nurse so I do understand allot of medical lingo. This however has me very puzzled. Now I do have some pain at times in the bend where my hip starts to my leg in the crease. I have had that pain however for years. Any suggestions? I would love for the Dr to see it swollen up bad like it has gotten. I never luck out with a cancellation however to see him the day of or the next day while swollen so bad.