I used to have a few children like this. One girl was always bleeding on her bum when she was teething no matter what we did. Both mom and I changed her immediately after she pooped, but every time she would bleed anyways. She would seem to get redder all day, even after the clean up.

We finally figured out that it was due to acid in the stool or urine. Even when the area was cleaned away, the acid was still eating away at the skin. We started putting Milk of Magnesia on her bum and it cut the acid as asap, then we would put Zincofax extra strength on her. The rash was gone in two days and never returned again as long as we kept the Milk of Magnesia on her bum after every diaper change.

I have never had a child get a diaper rash since at my day home, and heal them rapidly if they come to day home with one. All the parents use it now and diaper rashes are a thing of the past.