lesions are like some sort of growth or skin tags
whereas the fungal lesions there will be intense itching and it will not be raised much from the skin surface and it uniformly spreads over the peri-anal surface with some color change.
If you consult your dermatologist
they will easily diagnose the condition and guide for appropriate treatment. Smear from the lesion and culture will reveal fungus and very easy to get treated.
Wish your child a speedy recovery.