I blacked out while smoking

i've been smoking weed for a few years now, everyday. i've never had anything weird happen to me until the other day. i had just smoked with one of my friends and we were standing and talking to someone. when all of a sudden my vision went black and it felt like i couldn't speak. i could still hear everything everyone was saying. the next thing i know, i'm waking up on the floor. my friends said i had just collapsed. they had tried shaking me to wake me up. they said my eyes were open and were twitching back and fourth, but i wasn't responding to any commands. when i finally woke up, my hearing was stuffy. almost like i was underwater and people were yelling to me. has this ever happened to anyone before? i'm just curious to know what caused it exactly, if it's something i should avoid doing later.