I’m sure there are positive anecdotal stories and bad ones. I’m our case, it was my husband’s doctor googling that led us to suspect our newborn had a dairy allergy. When we brought this up to the pediatrician’s office we were told it was highly unlikely because it’s so rare, but I could try an elimination diet if I really wanted to, but he most likely just had colic. Nope, he had a dairy allergy and other protein allergies on top of that one.
Switched from breastfeeding (couldn’t identify all of the allergies) to a hypoallergenic formula and we had a completely different kid.
We did involve his doctor in all of these decisions.