??? I would be more concerned about the comb shrinking in size. I am putting colloidal on my Road Island, because it looks a little smaller, but it was pale. My rule of thumb is if what I am giving to them, or applying to them can have adverse effects I want to know exactly what I have going on. But with the case of applying colloidal, there is no adverse effects, and only beneficial. As for applying Poultry Booster, it's really cold out and the wind chill has affected them. Again, it's just a booster and no adverse effects. As for the Dewormer we use from The Poultry Store, we do that Fall and Spring no matter what, and we continue with a maintenance dose 2 a month Again, it can't hurt. As for Diatomaceous earth, we always use that in their dusting box, and it get's sprinkled into their rooster area. Their dusting box is under the overhang and they love that all year round.
None of these things are invasive. But if it is a case of ring worm it would appear on their combs as pale combs with a mottled whitish appearance and it can spread to their eyes, to the flock and to humans. Addressing such appearance up front with colloidal is a step to ward off "if it is" and can't hurt even if that is not what it is. Along with other things, dehydration can cause a comb to shrink.
So, I am keeping an eye on her comb to make sure it really isn't shrinking. That would concern me a bit more, as would a change in behavior. Keep in mind that chickens usually do not show sickness until it is rather progressed. Like any bird it is a natural defense against becoming preyed upon. That is why keeping a close eye on their combs is key to keeping them in top shape.