I've been sitting in Starbucks literally all day studying for finals, and I've had A LOT of coffee (I had a cup before I went to Starbucks, and then a large cup there). I'm a big coffee drinker so I wasn't worried about how much it would effect me. All I had to eat this morning was a piece of toast with butter on it, and then at 4 I finally bought a turkey sandwich. As I was studying (after a million hours, it seems) I started to have this feeling of impending doom. I couldn't concentrate AT ALL and I started getting super anxious and n*. I had to leave. So I left. I've calmed down a bit but I'm freaked out as to why that happened. Also, I drank some water but it wasn't purely water--I've had a cold and I've been putting this emergen-c type stuff in it (something I got from a health-food store...) so I'm thinking it's a combination of coffee, a lack of pure water, not eating and then stuffing my face really quick, and stress from studying for finals. help :/