I personally haven't tried oregano oil, but have tried coconut oil. Coconut oil is apparently one of the most healthiest fats you can eat for many reasons, not just antiviral or antifungal either.

I did not feel I reacted too well to it, but that may have been part of die off. But I stopped using it. I rely mainly on diet and other fats like butter (which apparently is also a mild antifungal). I do well on that.

I am not sure what tests can prove systemic candida becuase I know how notoriously inaccurate they can be for many people who are extremely ill with candida/yeast and nothing shows up. The only way to really know is checking a list of candida symptoms online and doing a trial candida diet and seeing the reactions.

Candida dying off from being denied sugars and high carbs/yeast is pretty telling in itself that you got a problem there. Headaches may occur, sleepiness/drowsiness, dizziness, nausea, diarreah or constipation (alternating), moodiness, crying, depression, nervousness/anxiety, more wild dreams may occur, spaciness, coated tongue, flu like symptoms, worse itching or thrush, basically a worsening of your existing symptoms and possibly some new ones etc.

I find that the best test is trial by diet! And the improvements that may follow after adhereing to it for weeks is rewarding. Something should start to improve after the typical initial worsening. Once the yeast levels are lowered and once your body has eliminated the toxins from the die off, you should start to note improvements. Unfortunately it's a hard process because as it's dying off you become temporarily more toxic in a way and also I read somewhere that for a while some yeast will try and live off the die off from other yeast. So you're in a state of die off and flare ups/growth for a little while this process is going on.

Oregano oil may aid the killing of yeast, but is not advised early on in the programme until you have first been on the strict diet for a few months first and gotten through that die off (which can be hard enough on its own without adding more to it). Don't forget, natural antifungals like butter and coconut oil can be more than enough and many have to start on very low doses of coconut oil. Oregano oil is even stronger if I recall and should only be used later on.

You can use garlic in foods too to help. But watch out for the stronger more potent antifungals at first. You do not want to make yourself too incredibly sick because it takes the liver sometime to get rid of dying/dead yeast and you can become very toxic from that alone. If too much of them are killed at onetime aggressively, you could find yourself in a real state.

I remember the first time I did the diet alone, without any other additions of antifungals and I was quite ill for weeks. I felt drunk from the yeast alcohols being released during their death and kept lying down for sleeps and had the typical headaches etc. IT does pass, but it takes time.

Apparently yeast can be cured from diet alone, but the other stuff is helpful. It's just that it takes vigilance and patience. It's not just about "killing yeast" it's about getting rid of the junkfoods and other foods that feed it and about building up the health of the body and immune system. Healing doesn't happen over night. Your body will over time, if given the right nutrition should rebuild and improve. It may not be optimal if other issues haven't been addressed that might be the reason for the yeast to overgrow in the first place, but it is definitely helpful.