The diaper rash is one of the few things that “fit” into the 10 signs of pid – chronic skin infection (and failure to grow). You had mentioned that Dell has been healthy – no colds, sinus, ear infections. That is supposed to be one of the hallmark indicators of pid when combined with low immune cell counts. Dell has always had cell counts at the low end of normal until just recently when they started dipping below acceptable levels. That makes me wonder if his latest low counts are a result of all the different treatments to suppress in the past year as opposed to an inherited deficiency.
Warning signs of primary immunodeficiency: