The world is much more complex than this, unfortunately, there are a significant number of etiologies which result in CFS-like symptoms, it's one of the less studied umbrellas out there.
Lyme, babesiosis, rocky mountain spotted fever, etc, all negative. I also did a urine Lyme DNA test a while back but looking back on it, apparently that was not an extremely reliable test (though the western blot has a decent amount of false negatives as well).
I believe it's a chronic yeast infection that's slowly traveled up under the skin of my left leg for the last 7 years or so. It started out as athletes foot in college, and then when I got past the point of being too overwhelmed to treat it, it had set in pretty well.
I wondered if the two were correlated, but over the past few years I've had increasing leg pain in that area, and the same pain in my toe where the infection was. Of course, the nature of this infection is that it seems to be resistant to many OTC classes of antifungals, so it did not budge. The most effective agent was carvacrol/thymol, which is extremely broad range (even against MRSA), but it macerated the skin to a point of strong pain, bleeding, etc, all that jazz. Even when it cleared up on the outside, there was a deep white patch under the skin that you could see under the (healthy-seeming) skin, which, of course, is its own unique class of horror.
About a year ago or so, I finally broke and decided to get rid of the skin infection no matter what. I basically mixed isopropyl alcohol and table vinegar and put it in the skin after removing the top layer of dead skin, which as it was an open wound was extremely painful. I used the reasoning that I could temporarily damage the nerves with overexcitation via the isopropyl alcohol stimulation, and that reasoning panned out after an excruciating several days, after which my nerves were damaged enough to no longer hurt under the raw vinegar and alcohol combination.
That at least cleared up the surface infection until I was on the Appalachian Trail this year (which, yes, I did my two months on it with chronic fatigue + post exertional malaise (!!!!) !), where, more than a year later, the infection inexplicably came back again.
I found niacinamide in my search for treatment-resistant infections, and it cleared up the surface infection within an astounding 2-3 days. I started taking it orally, and became extremely sick, it felt like I was being poisoned and doing a mini-chemotherapy of sorts, so I slowed down and began taking silymarin and NAC to help preserve liver and kidney function (which seems to still remain okay so far).
The process of treating it has been painful, as the initial days caused a huge flare in leg pain in my left leg corresponding with swelling of the lymph nodes almost exclusively on the left side of my body, oddly enough (though it seems to have balanced out, a bit). I was in the emergency room on my birthday last year due to the leg pain, and they couldn't figure it out so they offered a potential umbrella diagnosis of complex regional pain syndrome.
It's hard to keep up with dosing as I do have a bit of an aversion to feeling sick -- it quite literally feels like I'm being poisoned! -- but, my CMP from even this week came back okay, and I'm getting a feeling of underlying 'rightness' despite the transient negative symptoms (including having to pee every 2-3 hours...not fun).
I've had maybe two dozen doctors, both in and out of the ER (6 visits in the last year or so), or so give me that look of not quite being able to know what to do. I applied to the internal medicine program at the Mayo Clinic a few months ago and got a form letter turning me down. It's not due to incompetence, it's just that there is a long tail of extremely complicated conditions that categorically fit an umbrella of symptoms, but are extremely hard to actually track down (and the semi-binarization of medical specialties makes cross-disciplinary diagnosis extremely difficult for these vague kinds of conditions).
I'm sitting here now and can feel the leg pain when I focus on it, for example. But I think treating it is worth it -- especially as one has to work to live in many circumstances! That said, this does not underpin how grateful I am to at least have one avenue -- whether it's temporary or not -- where I can have energy.
This also doesn't cover things like the mast cell sensitivity (diagnosed as not MCAS by _two_ separate immunologists, though they both fall in the tryptase-test-philosophy camp). I react to everything, including All Free and Clear detergent, for example, and with food and such sometimes it's just eating tons of meat (it's pure muscle protein and fat and doesn't have things I can react to like lots of plants do) and multivitamins to cover the nutritional gaps.
I wish it were as simple as just having Lyme disease, as I think that would be much, much easier for me personally. But, I suppose to keep living we have to accept the limitations that we have (and unfortunately this is not the only journey of limitation I'm on -- I also have autism to a mild-moderate degree! That would be enough challenge for a normal lifetime as it is. D'''':), and I had a number of years where I really struggled (like, really really struggled). But all of that said, I think although it's taken a few years, I've come around the bend in starting that process of eventually accepting the challenges I've been given, and I am on currently on that particular upward walk of learning to enjoy the life that I do have access to in the meantime. It's not perfect, and I have a lot of big bumps in the road, for sure, but the slope for me is pointed up, and that's what I wished for for years. And I'm enjoying life a lot more than I have in the past, on average! :')))) <3 <3 <3 <3 :'))))
Hope that answers your question.