Hi Denise,
Are you able to tolerate any compression? Compression is commonly used to combat edema and is also useful for POTS as it keeps the blood from pooling down in the leg. In fact ACE wraps were required for a group of CRPS patients who had side effects of fainting from a clinical trial of oral sympathetic blockers since it lowers blood pressure.
With swelling such as you have compression can be tricky as you don't want it too tight but it may be worth a try. Before making any investment I would recommend just using an ACE wrap since it is easily adjustable. Get the kind with a Velcro tab instead of the metal clips. They are much, much easier. If it is helpful there are all kinds of lymphedema compression wraps that are easier on/off than traditional stockings.