Frey syndrome?

I took my 15 month old to the allergist today because he has pretty bad facial eczema and breaks out a lot on his face and around his mouth when he eats. He didn’t test positive for any allergies b they think he might have Frey syndrome. Everything I’ve read said it’s pretty rare but can happen from trauma at birth like using forceps. I had the easiest birth literally he was out in three pushes. Does anyone have any experience with this? I’m going to follow up with the pediatrician and see what she thinks I was just curious if there was any experience here.