Unfortunately I have found that sometimes a very HARD workout will cause one to v*. I have never worked myself that hard but I ONE time after a lot of crunches I felt n* for the entire evening and one time I pulled into the parking lot at the Y in my area just in time to hear someone v* from their car (I had to assume it was after their workout and that they were not ill).
So...it may have been but I feel that if someone was s* they would not go in the first place, right???
Try to find the strenght to go -- working out is a terrific stress reliever!