I have had it several times too and i think it comes down to pre-coital hygiene.
I don't mean to imply you have poor hygiene, but sometimes when you expect things to be kind of smelly anyway it gets overlooked.
I'm referring more to your partner than youself, but it can't hurt for you both to have a wash before hand.
I honestly haven't had it for ages now, about a year, and i put it down to insisting that we both wash before.
I'll have a bath in the evening, which i like to do anyway, and my hubby makes sure he washes his bits before bed if he has been remotely sweaty particularly under his foreskin.
If you can smell it without putting your nose upto it, it needs a wash.
Treatment wise i swear by Canesten Oasis.