I was under stress yesterday and was suddenly very week with shallow breathing. I laid down and drank a coke until lunch time. I am a 55 year old male in good health. Height 5'10 155 lbs.

Difficult . Difficult to know what this was from what you describe. Heart, blood pressure and lung problems could cause this as well as other conditions. Some of the possibilities are quite serious. I urge you to get checked out, physical exam and electrocardiogram. Good luck.