Got Stuck By A Nail In The Kneecap. Went To

Got stuck by a nail in the kneecap. Went to nurse practicioner to get a tetanus shot. While there, I started sweating profusely, my mouth got very dry, I became nauseous, and then I got very light headed and passed out in the floor. They checked my bp, heartrate, and it was normal. Just wondered what the probable cause of me passing out was from and if I need to seek further medical treatment. I feel fine now.