I Took My Two And A Half Month Old Granddaughter

I took my two and a half month old granddaughter to see an aftercare pediatrician because she was still congested after two weeks prior of seeing her primary pediatrician. As well, her tongue was yellow. The pediatrician thought it was funny laughing while she stated she'd never seen or heard of such a thing. She did prescribe nose drops and an antibiotic for her though. I will followup with PCP.

Shouldn't a pediatrician know about yellow tongue and it's causes in infants?
Or, at the least, done some research for appropriate treatment?