I am 27, male, have been suffering from short episodes of sudden fatigue, which I suspect to be due to shortness of breath. I feel the episodes of fatigue when 1. When I do exercise for a while and sit down to take rest. 2. After eating heavy meal. Also when I sit in a small, enclosed space, (such as small meeting room) I get the episodes of fatigue very often. What medical tests are needed to find the cause for this illness. Is it Shortness of breath.