Hi Callie,
I have no answers for you.
Kris had a similar thing happen with his chemo. He too would pass out and I would have to shake him to rouse him and get him to take a breath. It was very frightening. We never did get an explanation from the chemo docs.
I am praying that Dons CT shows no nerve involvement. One day at a time Callie.
Hugs and hand holding to you, Tammy

Caregiver/advocate to Husband Kris age 59@ diagnosis
DX Dec '10 SCC BOT T4aN2bM0 HPV+ve.Cisplatin x3 35 IMRT.
PET 6/11 clear.
R) level 2-4 neck dissection 8/1/11 to remove residual node - necrotic with NED
Feb '12 Ca back.. 3/8/12 total glossectomy/laryngectomy/bilat neck dissection/partial pharyngectomy etc. clear margins. All nodes negative for disease. PEG in.
March 2017 - 5 years disease free. Woohoo!