What Does Hyperpigmentation Below The Knees Indicate?

My friend has had what looks like the google images of dvt (dark discoloration Below the knees) for over a year with reoccurring ulcers in his ankles. Many trips to the er for pain was told it was cellulitis and given antibiotics. Taking the medication for two days from his last visit his feet developed blisters which broke most all the skin back from his toes to just above the ankles. Its been a month now and hes been to the clinic, hospitalized for several days, and seen wound care but no answers. His feet blister almost daily, I have no idea how that much skin can keep blistering off everyday, but now these blisters are on his hands moving up to his elbows and within hours of wound care putting on compression tubes they progressed up past his knees up his inner thighs. Only thing Ive ever seen like it was from some one whom had put their hands into sink water with drano. This makes me wonder if its some kinda toxin problem...I know he has 2 partial bullets still lodged behind his ear from 2010 and I often wonder if the metal would cause this from such a distance away from his extremities? Have you any notion as to how he could be helped or what might be the cause of this discoloration, ulcers, and now repeated blistering?