I don't know anything about that doctor, but I did suffer from type IV delayed food sensitivity in the early stage of my ME. I don't know whether the sensitivity was due to ME, or the ME was due to the sensitivity. I was unable to find an allergist or immunologist who could do any reliable testing for type IV sensitivity. I did encounter one quack who insisted that his skin test would work ... despite it measuring immediate histamine reaction when my type IV reaction had a consistent 48 hr delay and didn't involve histamine response. No, I chose not to pay $200 for his "of course it will work" test.
If Dr. Dantini won't explain why his test works on delayed sensitivity, or that the test will provides results in less than your normal delay time, I recommend saving your money. I do understand the desperation, but fake tests won't help.
You didn't say whether your sensitivity is type IV. What is your delay time, and is it consistent? Mine was a precise and consistent 48 hrs (+/- just a few minutes).
A rotation diet did stop the reactions. I think I used a 5-day rotation, and that avoided the reaction unless I made a mistake and ate a food from the same family too early. Weird effect: it also abruptly changed my delay to a precise and consistent 17.5 hrs, which doesn't fit the normal description of type IV (48-72 hr delay).
I did manage to cure my food sensitivity ... accidentally. I made some curry with coconut milk that turned out to have spoiled. That flushed out my digestive tract quite well. That was the end of my type IV sensitivity. My guess is that I had some microbe in my gut that survived antibiotics, but the food poisoning managed to remove enough that the good microbes could finish it off. I'm not recommending this as a (risky and very messy) treatment for type IV sensitivity, but it might help you to know that it is at least possible to cure it, and that it might have a microbial cause.