Hi, I'm Interested To Know What Would Cause Someone To

Hi, I'm interested to know what would cause someone to complain of not feeling well while sitting on a bench and then shortly after becoming rigid, head tilt back, eyes roll back, uncontrolled trembling, and foam at the mouth. EMT's came and administered an IV solution. Blood glucose was 126. EMT's said O2 saturation could be better. Before this occured the individual rode about 15 miles on her bicycle and was probably a little overdressed. This is not the first time this has occured. About 6 mos. ago this same set of symptoms happened while she was riding on a track with her bike. Very curious to get some info on what might be going on. Patient is Female, 55yrs. old, maybe 10 lbs. overweight and lives alone. Any info would be much appreciated. Thanks