if you try to wipe it off with your finger,or with a wet rag, if it doesn't go away or starts bleeding then it's thrush. if this is the case, then you can go to walgreens and get gentian violet, it stains clothes real bad and will turn his mouth purple temperarily but it works way faster than what the doc will give you. i highly recommend it.
If you can't whip it off the babies tongue then yes dd may have thrush, If so gentian violet for YOU and BABY for three days and there after dip ANYTHING you put on your boob in vingar because it kills the yeast from re-growing again... But in the past I have had problems when I was nursing my kids and I found if I dip the pacifiers once and night and once during the day also dipping my madela breast pump cups also in vingar, My son and I have been clean frm any signs going on 2 months...
Hope it's nothing ..