I think you have dyshidrotic ecmaea, not fungus. This form of eczema produces the kind of small blisters you describe. Cause is unknown. You treat the symptoms as they arise. Mostly, cortisone (steroid) creams are used, though there are now alternatives. You doctor can recommend others if needed. All such creams can do is make the condition better--it recurs when it wishes, and must be treated again. In time, it often goes away, sometimes for long periods.
I can't explain the color change. Perhaps a skin doctor can do so at a visit.
Take care.
Dr. Rockoff