|I use vinegar(1 cup) in my final rinses too, each and every time. So I doubt that it's that. Besides, vinegar is supposed to rinse cleanly. And fix the PH of urine also.
How much washing soda are you using? I do use washing soda too(2 tbs), but in addition to soapnuts. Not alone. Mostly for the clean smell, the soapnuts alone cleaned just fine but I still thought my dipes had a faint urine smell.
Maybe I shouldn't stick my nose in diapers????
Anywhoo, do you hang dry or dryer dry? Any fabric softener that might cause buildup? I know that Calgon is technically a "water softener", but is it possible that has accumulated in the dipes? Mostly since it was in the final rinse?
How old are your babes? Older children have more concentrated urine, so when they pee, boy you know it! But usually kids smell worse in posies than when they pee than cloth.
Rash.....yucky. Man rashes suck! Could be a sensitivity to something in the dipes. Maybe it's what's causing them to reek.
When you strip them, maybe just use hot water and that's it. No chemicals or additives. Nothing but water. Then try them again. Maybe little one won't get a red bum next time?
I don't know if I helped you or not, but man I feel for you! Keep the faith sister! All us mamas will do our best to help you figure this thing out!