We had this problem with my DD a few weeks ago. I think it was actually linked to her teething (she's getting eye teeth now) . Her wee seemed stronger or something
and her skin seemed to react to it. My mum said my brother was the same (he loved hearing this as he's 21 now
). My DD has red hair and pale, sensitive skin (with you there Donna!
) I used a fleece liner and changed her often, but it lasted a few weeks or so before disappearing at the same time her teeth came through. It has gone now. It didn't seem to bother her either. I know you've been struggling with it for a month now but you may find it will go when the teeth come through. Also, I normally only put in a small amount of detergent when I wash nappies, and most of the cloth mums I know do this too, less than I would put in for a normal wash.
Hope you guys find a resolution soon!