good evening, by the complaints u have stated , i feel ur daughter may be having lactose intolerance
, which is common and transient. so there s nothing to worry about. what u have to do is avoid the use of diaper , keep the area clean and dry , avoid cleaning hie diaper area with a force , but instead just compress area with a dry tissue to absorb the moisture. get a stool examination done to rule out lactose intolerance- stool for reducing substance. currently u can use any anti diaper rash cream
available with u , along with that to reduce the pain u can use lox 2% gel , applied to area will reduce the pain.