Any idea what this rash is?

[alaskamum]

DD is 11 days old. I'm using prefolds and covers on her. She is breast-fed.

(ETA): She is also a little jaundiced--but not bad; bili level was 13 today and ped said we could stop checking.

When I changed her this afternoon, I noticed her butt crack looked kind of yellow--as if maybe I hadn't cleaned her well enough after her last poop???

But, as I gently tried to wipe it off, I realized that it wasn't dirty...it's some kind of rash.

It's
yellowish
raised
by her anus
it doesn;t seem painful; she fusses a little when wet or poopy but not like she's in pain

Any idea what it is? The only thing I could find was that maybe it was a form of cradle cap in the diaper area, (and my other two kids had BAD cradle cap) but I'm not sure what I would even put on it.

Any ideas?