Hi H.,
Here is a suggestion that has proven itself for me through four babies. It is a product called gentian violet. My pediatritian recommended it years ago. It is a natual anti-fungal that works for yeast also, made of plant extracts and it is relatively inexpensive and can be purchased OTC. Call your pharmacy to make sure they carry it.
It will stain your babies mouth temporarily purple,(for about 1 day) and if you nurse, it will stain your nipple area as well. If the rash is on your babies diaper area, you can treat that area as well. The irritation will dissapear usually by day 2 and within 3-4 days the rash will be gone.
Directions:
Day 1- saturate the end of a q-tip in the liquid. Rub around inside babies mouth making sure to coat entire inside of mouth, i.e. all gum tissue and under tongue. If nipples are affected, use new q-tip, saturate in liquid and rub over affected area.
For diaper area-saturate q-tip and rub over entire affected area.
Day 2- Repeat as done on day 1.
That's it. If you have any questions, feel free to send me a message and we can go from there. I am happy to help, if I can be of any. Hopefully one of these wonderful suggestions will work and you will have a happy baby soon.
A.