I have no clue. I get frustrated too because my sons still comes and goes and I do everything I can to help it. If it doesn't get better I would recommend to take her to a dermatologist and let them know what's going on.

@jaxmama, thats what the doctor said it was but shes had it for soooooo long and she got it from an antibiotic shot the doctor said it would happen but why is it taking almost 2 months to go

Looks similar to a yeast diaper rash. If it is that, then it's just from her skin always being warm/wet! Which causes the yeast to spread and grow because yeast is fungal. Take her to get checked out. It's nothing to worry about but it is something that should be treated because it can get worse and eventually be sensitive and uncomfortable to her. Google has different pictures of rashes that you can try identifying and comparing in the mean time.

Try letting her be naked. And use coconut oil instead

Has she always used those diapers?