OMG talk about a vacation going south! I'm glad you lived to tell about it : )
Being that you were in the islands, is there a chance you had any exposure to red tide or similar organisms? On top of a crowded theatre, that could cause a severe reaction like you had.
My fingertip Oxymeter dropped below 80 in the ambulance and I woke up an hour later in an emergency room. Nobody ever talked about it. Later I saw a map of coastal red tide and where I live just happened to be red tide central! http://myfwc.com/REDTIDESTATUS
"A harmful algal bloom (HAB) is the proliferation of a toxic or nuisance algal species that negatively affects natural resources or humans. Scientists prefer the phrase “harmful algal bloom” to “red tide” because blooms are not always red and are not related to the tides." http://myfwc.com/research/redtide/general/harmful-algal-bloom/