What Causes Sudden Dizziness And Cramps Under The Armpit?

one minute pls. ...I was with a friend in Manila this week. She collapsed in front of me, a dead faint. She said it happens once or twice a year, always after she feels cramps under the armpit, and sees green visions. Symptons include dizziness, but she showed no signs of stroke...no drooping, slurred speech etc. She fainted twice more, about 15 secs each time, on the way to a couch. All with 5 mins. Hosp tests are inconslusive. What could that be? She is in recovery after big op 6 weeks ago for burst appendix, and some septamsemia.