Bittertruth,

Shivvering because of chemical weapons will bedifferent than jerking as shown in many videos. They were shocked, pupils were dilated, but that can happend from many chemicals not the Chemical weapons as world understands, in one or two videos salivation is there but in many there is not so that rules out the possibilty of chemicals weapons. because  , if it was Sarin, VX, salivation will be intense, Also jerking does not qualify for symptoms of chemical weapons. there will be almost non stop salivation and tears.

Shivering will be like when flies shivvers before dying when sprayed some organophosphorous chemicals, 
The only  pronounced evidence is  dilation of pupil. which in turn also can happen from several other chemicals, not only from cheimical weapons.