What Causes Reddish Rashes With Yellow Heads?

My husband started with a poison ivy rash (he gets them a lot no matter how hard we try to keep him away and keep it out of our yards and even the neighbors yards). Anyways, the middle is starting to turn yellowish??? It doesn't look infected otherwise. It's not hot to touch, not streaking, not blistering anymore. Just still deep red with a yellowing middle. I'm thinking maybe it's getting fungal???
He also gets eczema, but this doesn't look like that.