Is Fainting After/During Sex Normal?

I am 26 Female. I faint while having sex or during sex sometimes. It happened quite frequently in recent times. As soon as I feel that I am reaching the peak of arousal, I faint suddenly. It take 2-5 minuets for to come back to senses. Sometimes I feel breathless and pain in cheat. My husband is worried a lot about the condition.

I would like to know if this is quite common. I was going through stressful routine since a month or so. Can this be a reason? Please reply if you have went through it before. Thanks.