No, you couldn't, as it's not a diagnosable illness-it's just what a doctor might suggest when he doesn't want to do any further investigation.
Don't ever accept it.
My daughter was told she had CFS and this led to her being given entirely incorrect advice, which had the effect of worsening and prolonging her illness.
So it is very important that you continue down the path you have followed so far-I'm very impressed-until you get the right answers.
It won't be easy, and you will have to take complete control over it as you are probably venturing into an area of very shaky medical knowledge.

My daughter in fact has ME. This is Myalgic Encephalomyelitis.
I have no idea if this is what you have, but fatigue is not usually a factor.
She was so disappointed with the complete lack of medical care, knowledge and assistance available to her that she embarked on an intensive study of the illness.
The result is her world renowned website, and she has also written several books.

Here's a link.
http://www.hfme.org/themesymptomlist.htm

Fatigue was not one of her symptoms, so it was strange to be told she had an illness with fatigue as its main symptoms.
Her main problem is that her heart doesn't compensate by pumping faster when she sits or stands.
You would do well to read a bit of her website to see the battle she has had, and you may pick up some good advice on tests and things.

She has now begun improving since getting seriously ill over 13 years ago, and while it is impossible to say which of the multitude of things that she has tried and/ or taken has been responsible for this marked improvement, she has settled on a diet free of chemicals, processed foods, sugar, dairy, nightshades, alcohol, grains, soy and so on.
She has fresh vegetable juice daily, organic eggs now and then, organic meat and veg. Coconut milk is her main fat, and she makes fruit smoothies with this for all of us. Great for breakfast.
Keep up the intense study of your illness, and disregard any thoughts of the fake CFS.