The worst diaper rash ever

Baby's been pretty lucky thus far in his fourteen months - he's really only had one episode of diaper rash thus far, despite the fact that he seems to have somewhat sensitive skin. That is, until this week...

He woke up Monday morning with the worst diaper rash I've ever seen (given that Baby is my only child). Poor kiddo's bum was totally red and every time I touched it, he would recoil and scream and cry. Poor little guy. Being a first-time mom, I called the pediatrician, who recommended a thorough course of Nystatin cream and Balmex/Desitin/Triple Paste/Boudreaux's Butt Paste. After he grilled me.

Oh yes, he grilled me. Question after question about what he'd been eating, and he asked me at least ten times if I'd given him citrus (despite his warning at Baby's twelve-month-old appointment to stay away from citrus). I sure hadn't. And neither did Husband. So what has caused the trouble?

I have run through my head a million times what I could possibly have fed this poor child that would cause him such agony and I'm at a loss. The only new food I can come up with that he had was my special homemade buttermilk pancakes on Sunday. Which did indeed have buttermilk in them. And I know that if I'm out of buttermilk, I can "make" buttermilk for recipes by souring milk with lemon juice. So maybe the buttermilk disagreed with him?

Then Husband came home from work today and remembered that Baby had spaghetti-O's for dinner Friday or Saturday night, and tomatoes are citrus, so perhaps that was the problem. He has had them before, though, so that doesn't quite add up for me. Baby is feeling better today than yesterday, though his bottom is still awfully sore and red. He's nowhere near as crabby, though.

If only I could figure out what caused this whole mess. Husband heard from his dental hygienist recently that when a baby's molars start to come in, they release some kind of chemical that can cause pretty serious diaper rash. Has anyone else ever heard of this? It sounds like an old wives' tale to me, but who knows? That would explain things, since a molar poked through Baby's gums last week...