What Causes Pus Filled Blisters On Legs Post Laser Ablations?

Yes. I am pretty healthy for my age(80), 196 lbs (i m dieting). I have fat knees. I ve been treated for venous insufficiency now with 2 laser ablations on my left leg which has an ulcer that oozes at times. I m supposed to wear compression hose, but when I do it becomes a touniquout below my knee. Help! I am also incontinent.