Undiluted oregano oil can burn the skin, and it it MUST be diluted when taken internally. First physician, do no harm...is a rule we follow very closely on this forum. So if you're going to suggest people use substances that can indeed cause harm, please be sure to completely explain how it can/does cause harm and what to do to prevent it.
Oregano oil also can reduce iron absorbtion! Many sites recommending oregano oil also recommend taking an iron supplement when using it.
There are many herbs and oils that are antifungal that don't need warnings and additional supplements.
No one EVER needs to take "high doses for months" of anything to rid themselves of a fungus "under the skin"...but they do need to be aggressive in dealing with the cause (which is not a lack of oregano oil, but is a terrain that's conducive to overgrowths of fungus).
The original poster didn't actually seem to be asking a question for themselves - they appeared to be trying to generate hits & traffic/posts for their site.
Btw, I've noticed that you don't seem to know the basic tenets of this forum. We teach and base our protocols primarily upon the works/teachings of Dr. Christopher & Dr. Schulze . So if you're not familiar with or well-versed in their concepts of healing, then please familiarize yourself (hopefully utilize the concepts & therapies yourself), before offering others your opinions/advice. Thanks!