I'm going out with an exciting new guy but something terribly embarrassing has happened.

He likes trying out different positions and while we were in one of them I was suddenly hit by a bout of what I can only call "vaginal wind". It sounded simply dreadful and I didn't know what to say. What on earth is the matter with me?

Nothing is the matter with you. You are not producing this wind. What's happening is your new man is accidentally pumping air into you and it's coming straight out again. Noisily. This is very common in certain positions, particularly the "doggy fashion" ones. You might prefer to avoid these in future. Also, some people say using a vaginal lubricant or a spot of contraceptive foam, will help. If it happens again, the best thing is just to treat it light-heartedly. Your new bloke has probably encountered it before.