Sounds like yeast rash. Use some Nystatin ointment and it will be better within 24 hours if that's what's wrong.

 I'm not a cloth diaper expert. But i have Bum Genius 3.0. My instructions say NOT to use vinegar or baking soda.

Mine say... cold wash with deterent, followed by hot wash with detergent, followed by and extra rinse.

Also i do not soak mine overnight. I wash whatever i used for the day every night. So when i wake up in the morning i have a dryer full of clean diapers.

I would try avoiding the baking soda and vinegar. Is it possible they could be causing a reaction???

I have used cloth diapers for many years now.  I would not soak in vinegar or baking soda as those can irritate babys skin. You only need to do a cold water rinse and wash as normal. A lot of babies are allergic to disposible diapers but I have never heard of a baby being allergic to the cotton or microfleece cloth diapers :)

tina~

i have heard of babies being allergic/sensitve to the polyester in microfleece in CD. which is why a lot of WAHM diapers dont use the microfleece .http://www.doodlebunz.com/about-diapers (this website has info on polyester sensitivity)

i would say try getting rid of the vinegar and bakinsoda and if it doesnt get better maybe little jenny is sensitive to the synthetic fabric? does she react to any of her clothes that are on her skin for long periods of time?

 maybe it is because the elastic area is tighter...or maybe the combination of the tight elastic and her crawling..which may cause some rubbing..is irrating her skin

i'm grasping at straws....i have no idea if elimating the vinegar and baking soda would help..but it couldn't hurt 

Hopefully it's NOT what I am going to suggest but my DD's eczema started as a pimply rash in her diaper area before spreading to the rest of her body.  She's also fair like Jenny.  You might give her a rub down with lotion and see if you can feel bumps anywhere else.  Or put her by the window in bright light.  It was hard to see at first.  I thought it was yeast at first too but the doctor told me yeast would be in the folds of her skin, not the tops.   

 I agree, sounds like an allergic reaction or eczema. It would be unusual to have yeast there and  not anywhere else. How much did it change while she was in sposies and how long was she in them?