I am using prefolds on my 15 month old. She inherited them from her older sister. Howewer I recently noticed the smell after they've been washed (still a bit of a wee and poo smell) even though they are clean. I wash them at 60 degrees with persil non bio powder as I always have been doing. I run a cleaning cycle every now and then so I'm pretty sure my washing machine is clean. The moment I hung them to dry the smell spreads through the whole house. They're fine once they're dry ... but my house pongs when they're drying. Any tips?