Test for parasites, bad bacteria and gut health
You can get a stool test for parasites. I tested positive for blasytsis hominis. I recommend i-screen’s microbiome test from Australia it costs $199. Also Viome has a test in the USA and tests in Australia as well for the mircrobiome or the gut with is about the same price. It depends which country you are from.
Test for epstein barr virus
You can get a blood test to test for ebv. I tested positive to ebv
Test for allergies and food intolerances
You can get a blood test for food allergies and intolerance.
I found that I was intolerant to gluten, wheat, dairy and sugar. Giving these up helped me a lot.