Dizzy after orgasm?

Okay quick story is that i went swimming and got more exercise than usual, ate a bunch of mexican and got sick, then masturbated but tried to hold my breath so i wouldn't make noise as i had my orgasm and my boyfriend wouldn't interrupt my doings. When i stood up to go pee i was dizzy as hell and kinda off balance. Anything I've done that might've caused this? I don't usually get dizzy afterwards...