3mo formula changed from similac sensitive to enfamil ar. wet stools/diarrhea, awful diaper rash, & very pale yellow-green pasty stools. milk change?

That is possible : stools expected to change w/formula change until your baby's intestine adjusts to new formula. Greenish yellow seedy stools are a normal stool color for babies. There are many. Is the baby excessively fussy /gassy. If not, give it a bit longer to see how your baby is adjusting. Many changes & you can't tell what works. for rash-barrier ointment & air helpful can mix maalox w/it and apply