Answer

Thank you for the further information. I really appreciate the level of detail you have provided.

With regards XX XXXX question, this does not strike me as a "red flag" for any portenitally dangerous allergic problem. Initially I was worried about something called acrodermatitis enteropathica which is a zinc deficiency that manifests itself as severe rash around the mouth and anus (these kids are not happy and do not grow well).

It is certainly OK to try an antihistamine to see if that helps. You may want to ask your doctor about checking a blood count to look for a type of cells called eosinophils and an IgE level (these are markers for significant allergic disease). Since there may be some degree of bacterial overgrowth, you may want to try "probiotics" (healthy bacteria)--I use Lactobacillus GG (the American names of the brands I use are Lactinex and Culturel but I get the sense you are not American.

Finally if the rash does not get better you may want to ask that it be tested for strep. This is not very likely at your son's age but something to think about if it persists (this should not respond to antifungals however). A bright red diaper rash is often fungal so this does really seem what you are dealing with.

I hope this helps. Please let me know if I can help further. Best of luck and I hope he does great. Sincerely, XX XXXXX