Yeah you raise a good question. And I totally agree with you, that if it was a parasite or some other type of pathogen I would THINK that I would have some symptoms.
As I look closely though, I do have another symptom that indicates a fungal infection. I have dry cracking skin on the bottom of my foot, mainly on the bottom of my big toe on both feet and at the front of my feet. Did some research online and read dry skin on the bottom of the feet is often mistaken for just dry skin, but is always a low grade fungal infection. So with the feet, the tongue its making me feel like I do have a candida issue. Although, like Cheshire has mentioned I don't believe its systemic by any means, which might explain why in general I feel pretty good. I have no other symptoms other than those two things.
I decided AGAINST the anti-biotics my doctor prescribed, feel like that is just a band-aid and will only suppress my immune system more in the long run with the cortisone powder.
I'm going to buy some probiotics and start taking them today, I was on the lower side on my stool test for Bifidobacteria, so lets see if supplementing with them will help my tongue.
In the mean time I'm saving up some money to get some more testing done and work with a very well established functional medicine specialist within the next few weeks here.