I have been laying around worrying about this for almost 7 hours. What happened was I was doing a breathing exercise and after the first exhale, I got extremely dizzy. I took a shower to try and make the feeling go away, but I started seeing stars in the shower, and eventually got too dizzy that I had to turn everything off. After getting out, I passed out with my elbows on my knees for a few minutes (idk how long, but I could not function, only breathe.) I laid down for about an hour and I didn t feel anything except for a little dizzyness every so often. 6 hours later, now, I keep getting cold flashes (my head, hands, and feet get really cold), and it hurts the left side of my chest to lay flat on my back. It s not a sharp pain, it just hurts like a bruise, but I don t test the pain since I feel all of today is giving me terrible anxiety. My main question is, is all of this an anxiety attack (lay down and get some rest), or should I call 911 and go to the hospital? This is the breathing exercise: http://www.wikihow.com/Do-a-Breath-Control-Exercise-for-Rapping