Did they rule out cellulitis as well? It looks a lot like it. Also is he diabetic?
A few things I recommend to begin with are lymphatic and adrenal support herbs for the fluid accumulation. For the lymphatic system I recommend red root (New Jersey tea, ceanothus). For the adrenals I would go with jiaogulan, and schisandra berries. Good sources of vitamin C is also very important. Watercress, amla berry, or acerola cherry are my choices here. Vitamin C is going to be important for not only adrenal function but also for stabilizing the blood vessels.
The herb butcher's broom is also highly recommended for both its circualtion enhancing properties and silica content for strengthening the blood vessels.
Ozone bagging is HIGHLY recommended. You can sometimes find inexpensive corona discharge units on Ebay that will work.
If he is diabetic this will have to be addressed as well as elevated insulin levels in diabetes reduce circulation and damage micro blood vessels leading to problems such as gangrene.
If you can get back to me with a PM and let me know about the cellulitis and diabetes questions.