Toddler rash help!

My daughter only wears a diaper at night. During the day she is in her normal cotton panties. We haven’t switched detergents, diaper brand or wipe brand. Literally nothing has changed. She weighs 23lbs and we have her in a size 4 and this brand goes up to 37lbs for size 4.

However right on both sides of her hips she has had a rash that will not go away. It lessens when I’m constantly applying aquafor or a lotion on them, but they don’t go away. This is a photo of it at its worst. Currently it’s pretty faded. I should have snapped a photo but she is in bed now and it’s dark. What on earth could this be? It feels like her eczema on her face, maybe a teeny bit more ‘bumpy’ but surely this isn’t eczema on her hips all the sudden?

I am unsure if it’s related but she was recently at the doctor and had a fever and they said her throat looked irritated. I completely blanked and didn’t think to ask about the rashes on her sides of hips 🤦🏻‍♀️🤦🏻‍♀️