Mystery Twitching Illness in NY school

This news story is facinating and potential implications.
As you may know, there is a twitching illness in an NY school, mostly among some female students.

(a) As a cause, parents are concerned about possible chemical contamination. There are various ideas including possibly nat gas wells, drinking water, old spills, and others.

(b) On the other hand, some observers feel the cause is, as Freud reportedly observed, "conversion disorder" real disorder but psychosomatic based on certain stresses. Now some saying possibly transmitted by power of suggestion over social media/videos.

LeRoy Mystery Illness Symptoms May Be Spreading Through Social Media

I am going to guess perhaps it's (b) for most of the cases but can acccept (a) if that proves likely.