Re: Another Breastfeeding related question...

Oxalates should not pass through the milk, especially since it binds with calcium and other substances forming insoluble complexes.

It really sounds more like a flora issue. Normally babies get some flora from the milk and more from the skin itself. If the breast is being washed before feeding you could be washing away some of this flora. You could take some probiotic powders and apply it around the nipple before breast feeding to increase the flora in her digestive system.  The lack of flora could be interfering with the digestion of the sugar in the breast milk.