Snowbelt, was your CFS diagnosed with specific antibody tests?

In my personal experience the only time I had significant muscle spasms/twitching was after taking too much Mestinon one morning before eating. Sounds like everyone is different though, but just make sure you aren't taking too much Mestinon at one time in case that was a contributing factor.

Hi newmugg! - when i was referred to a big-city neurologist, by my local neurologist? The big-city neurologist ordered a battery of blood tests (the phlebotomist said the vial collection was a personal-record for him! Personally, I lost count!).
This was a couple years ago. I'm sorry: I don't remember the name of a specific antibody test, that would have indicated CFS.
On the other hand, there may have been blood-test results: that did indeed show an imbalance of potassium or sodium levels (which help to control these voltage-charged nerve-gates).
At the same time, the neurologist & staff also conducted a day-long round of nerve-stimulation tests, along with biopsies of the legs and arms.
With these test results in hand, the neurologist also had firsthand & direct clinical observation - of my CFS (a clincher, if you will).
Getting to the point: it was several years ago, when I was given the additional diagnosis of CFS. At that time? I don't think there was an antibody-test, that reliably indicated CFS. (** I do know - that researchers have been working on just such a test, which may now be available.)
Historically, a diagnosis of cramp-fasciculation-syndrome fits into the category - of being a ''diagnosis of exclusion''. Meaning: all other causes have been eliminated. It may be - that some potassium or sodium imbalance, was found in my bloodwork. While that bloodwork may not be a definitive test for CFS? It does lean in that direction.
Sorry - for such a long answer - to your elegantly short question! Ask your neurologist, next time - if there is now an antibody test for CFS. That's the first question I'm asking my neurologist, at my next appointment!
PS: I have complete confidence in my diagnosis of CFS (along with MG). Primarily because the prescriptions I take, to combat the symptoms? They work extremely well, compared to life without them. I take 3 or 4 daily doses of small amounts of baclofen and lorazepam. I get additional potassium at breakfast with a banana, and also take a small dose of magnesium (which helps the potassium and sodium do its job). MG patients might howl at the magnesium, but the small dose that I take? It definitely increases the efficacy of the CFS meds, by 50-percent or so. And I have never noticed the magnesium causing any increase in my MG symptoms.

I have generalized cramps, usually muscles in my legs, but can involve arms, hands and side (thankfully not all at once) at about 3:00am or 4:00am in the morning, at about the time the timespan is wearing off. I had them before diagnosis and my dad had bad cramps in his legs before diagnosis as well. So I assume in my case it is probably the MG. I did the chew a quarter of a dose of pyridostigmine last night and they eased for a couple of hours then I moved. Next time it will be half a pill! b.