In regards to Long Covid its a broad term that covers any lasting symptoms 12 weeks after the acute infection of Covid. About 50% of Long Covid sufferers meet the clinical definition of ME/CFS, via the Canadian or international definition. The total list of symptoms for that ME/CFS subset of Long Covid is identical to the long list for ME/CFS from other causes, but with slightly different prevalences. There is quite a lot of blood and other testing showing they are at our current understanding the same condition.
The other 50% of Long Covid cases are other things. Some people loose taste and smell, some gain diabetes others heart or liver disease. Covid attacks every aspect of the body so it can damage just about anything and we looking at a 50% increase in heart attacks and strokes alongside other vascular related diseases like POTS.
Hopefully that clears up the term Long Covid and its relationship to ME/CFS. Nowadays I would say someone has Long Covid subtype ME/CFS to be specific. However most researchers and doctors when talking about Long Covid are talking about the ME/CFS subset only, because all the other outcomes are known, named and often have treatments and they don't really know the true underlying causes of those anyway (based on what Covid did its probably viral damage!).
There is one other term out there which is PASC. This is usually related to people who were hospitalised with Covid and they have a similar condition but also a lot of them have a condition known about for a while after being on a ventilator. This often in studies gets called Long Covid but its not the same condition as a patient who had mild Covid and then went on to develop lasting symptoms. You have to watch out for this in any study because especially out of the UK this is what they have twisted Long Covid to become and this condition is at least in part de-conditioning and responds to physiotherapy.
Edit - and I just read a paper out of Africa that called mild acute Long Covid patients PASC. The terminology is all messed up! I have added no light to the situation whatsoever today!
So its a bit confusing because patients did their thing and then research did theirs and medicine did something different and then all the research found out a tonne of stuff and we have a advocacy marketing name and a disease and its all mixed together with some profit seeking misbehaviour.
doctor we are seeing now said ivermectin would cause my son to herx
Its possible but I think its unlikely to do anything of note at all unless parasites are present. Its an extremely well tolerated drug although ME patients often don't tolerate any drugs well. It doesn't do anything for Long Covid after a few studies looked into it so I would only bother if you think parasites are present, that should be testable from the stools and maybe in the blood or present on a scan (such as a tape worm or similar).