Hi A.,
a diaper rash that looks like a burn (especially if there are any little red dots around the edges) may be a yeast rash.
This could be related to your son's gut being out of balance. If he will eat yoghurt then finding a good yoghurt with live cultures to eat every day for a while may help bring back balance. I personally like Stoneyfield Farms.
Kefir is a yoghurt like drink that can also be found with live cultures. Then there are various straight supplemnts. I prefer the food options.
When my son was younger he had recurring yeast problems and would often develop a yeast diaper rash very rapidly. We found treating with Clotrimazole (an over the counter antifungal cream) to be effective though best if applied every diaper change until clear then two to four times a day (and especially at night) for an additional three to five days. Of course you may wish to speak with your sons doctor before treating.
Cloth diapers are wonderful, and we used them extensively. They will hold moisture near the skin however and yeast likes moisture (plus warmth and dark and high sugar environments). You may need to check and change the diaper a little more often at night if you do not want to move away from cloth. At least until the yeast is back in balance (if that is what it is). This is particularly true if you son poops at night at all. This may be the main transmission route.
Just remember, yeast is a normal organism of the body and everybody should have yeast cultures in their gut and on their skin. It is only when it is out of balance and out of control that it causes problems.
I hope this helps
K.