hi beanie, how old is your baby?
my baby has red patches on face quite often too and it's due to an allergy. it's actually quite rare that babies will react to their own saliva. it could be saliva mixed with dirt (which is a possible allergen). if so, then have to clean him up often or let him wear a bib so that you can frequently wipe the saliva off his face.
will you be considering a 2nd opinion?