?? internal?? If you think you need to rid your infant of yeast in the GI tract, you are on a misdirected crusade and will fail. Yeast (candida albicans) is at least 5% of the dry weight of a healthy persons poo and is present everywhere. Babies occasionally have overgrowth in rashes or inside their mouth because of baby activities-eating all the time & sitting in poo a lot. Irritating yes but dangerous no.
Depends. What do you mean by internal yeas infection? Is it on the skin or systemic (blood, urine, etc). The best way to treat a skin yeast infection is to keep the baby's skin super dry, over the counter yeast medication creams also work.