Question about adrenaline?

theres a girl i like alot and im a rlly good bowler im almost pro and she just wants to be friends im HONESTLY cool with that honestly but i had to bowl with her a couple days ago and idk how or why i had a adrenaline rush or a exioty attack i no its not spelt right but thats what the doctor says i had one of those anyone no why or how they happen?