My washing machine smells like a man's loo - HELP!

[coveredinsnot]

I've been washing my son's washable nappies in our machine for the past year, with no problems at all. But recently even inbetween washes, it's smelling like his nappy bin does when it's not been emptied for a couple of days - basically, like a really nasty men's loo. It's revolting! I've tried running it on a 90C wash with nothing in it, to kill off bugs. There's nothing in the filter - any other suggestions?!?!?

Try a hot wash with soda crystals. Also leave door open between washes to air the machine.

White vinegar!!!!! Pour as much as you can into drum about half a bottle and put on a normal wash! Also clean out soap drawer.

Thanks for your replies. I tried the soda crystals and that has seemed to help!! White vinegar next... Life doesn't get better than this...!!!