Re: Flats/prefolds aren't working out
I would definitely look into the detergent as being an issue. I think a lot of cd'ing rashes are caused by detergent residue mixing with urine / feces & sitting on the skin. I see that you've already stopped the prefolds. They are sized so you do have to move up in sizes to increase the absorbency or they can be really wet against the skin if they're too small. Adding hemp to them can help. By several months, I wouldn't think a prefold would work for night at all anymore.
dh (8/99), ds (12/99), 4 miscarriages, LO (May 2010), & Newb (April 2013)