Contact dermatitis

I HATE contact dermatitis.  Hate is a strong word, but it’s true.  I hate it.  My poor baby boy has it on his tummy and it’s awful.  We switched his diaper brand and that's when it started.  We switched back to the old brand but because the rash is right where the diaper rubs on his abdomen, it is still bad.  I have a plan though.  I bought like five different ointments, creams, lotions, cleansers BUT I tried them all instead of trying them individually for results.  I decided I will try a certain method for one week before moving on to a new one.  So here's my one week C&C (consistent and consecutive) plan:
Week one: thin layer of Cetaphil cleanser on his dry skin, layer of hydrocortisone 1%, Desitin diaper rash cream on the top to seal in the rest (this was his ped’s recommendation)  We need to do this at every diaper change – so I am hoping this will help his poor irritated skin!