I have the exact same issues that you describe. In addition, sometimes when I get into a very warm epsom salts bath the bottoms of my feet turn deep purple, almost black. (The first time I saw it I thought my feet somehow were quite dirty and I tried to scrub it off.)

Passing my hand over steam causes the same reaction that you have. Unfortunately my symptoms have become progressively worse.

Meds have had no effect on my color changes. As a result I have not cooked in well over a year-until last week.

Since I began my current round of tDCS treatments the color issues have greatly improved. The bottoms of my feet rarely change color. Steam is no longer effecting the color in my hand. During the past week I have prepared several meals with assistance. My hand no longer goes into a stiff claw.

I did not realize how miserable and dangerous these symptoms were until they started to improve.

You are not alone. There is hope for improvement!