See...you don't need me
Freezing is not guaranteed to solve the problem with a yeast.
Recent research has shown that Lavender oil has a fungicidal effect on Candida albicans which is great news for cloth nappy users. They used a 2% solution for 15 minutes to kill the yeast but they found that at lower concentrations it had a fungistatic effect (i.e. it doesn't kill the infection but stops it getting worse).
Adding Cider vinegar to the wash may also help. Don't use biological washing powder. Do a rinse cycle after your wash to help remove any traces of substances that may make things worse. And make sure your nappies are thoroughly dry before you use them again.
Try not to worry too much about going down the antibacterial route and try to stick to mainly anti-fungal only solutions. I say this as you need to get the skin and body back to its normal balance - many fungal infections are caused by an initial imbalance of the natural skin flora and fauna (!). Once the fungi get there and start to grow, they make their own little micro environment that suits their growth requirements. Having a few nice bacteria about to try and redress the balance may not be a bad thing. (yes, I know I am sounding like a yukult advert now )
Aren't you using bamboo nappies? Be careful with very hot washing. 60C will do a good job, but any hotter might be too hot for the bamboo.
The 'pond smell' is interesting have you not had any luck removing it yet?
Hope your DDs bottom gets better soon.
Very brain day atm, if I think of anything else I'll let you know
hth