Fainting after sex

My husband and I had sex tonight, after I got up to walk to the bathroom and started to feel dizzy and lightheaded with cramps all through my body. I ended up passing out in the bathroom floor and not remembering much. I’ve just looked online a little and it said intense orgasms can cause this and it could also be a serious health issue, has this ever happened to anyone else? I’m 20 years old and this has never happened to me.