A few episodes like this will definitely make you pay closer attention. I was hiking in higher elevations the morning before this happened to me for the first time. It was frightening. I caught a plane home later in the day and then the episode hit after I landed—extreme nausea, pain down one arm, cold sweats, and pain in my neck (thyroid). After a trip to the ER they told me my electrolytes were off balance. Probably due to hiking, flying, and coffee/tea. I know now when I begin to feel the slightest symptom coming on to hydrate immediately.