My 7-month-old has had brown on the back half of her tongue for 12 days. It’s quite noticeable now, and creeping forward. She’s on breastmilk and finger foods. I feel it might be thrush, as she recently has had a fungal diaper rash and my breasts are getting a definite intermittent burning. We were at the pediatrician today and he believed it was staining from food. Anyone experience this? I know thrush is typically white, but can it be brown?