''exactly identifying a specific cause disqualifies it from being ME/CFS''I don't think exactly identifying a specific cause disqualifies it from being ME/CFS.
This is a contradictio in terminis.
If the exact cause for your complaints is objectively demonstrable and causal, it does not meet the definition of ME. ME is a multisystem disease of which the cause is unknown and for which there are no objective tests to demonstrate the disease and symptoms. What you mean are secundary diseases such as infections in the mouth for example. They can be treated or not. Also many ME patiënts don't have pain. Patiënts with FM have pain.