Thanks for the information, I'm sorry for the delay in my reply, I hadn't seen the notification!
The most important thing here is the general condition of the baby: No fever, manages to drink (even if less than usual) and wets and soils his diaper, only monitor.
The basis of the treatment will be the hydration of the skin and other non-pharmacological measures:
It is necessary to apply, as often as needed, a moisturizer without fragrance such as Aveeno, Cutibase, Base Glaxal, Cerave and others. Personally I recommend Aveeno because it is oat based and it can help a lot, keep in mind that there is no maximum of times a day, you can apply it as often as needed.
Use a non-scented soap, and after the bath, avoid rubbing the skin vigorously: instead, lightly tap the skin to leave a thin layer of moisture, then apply the moisturizer quickly after getting out of the bath.
In the absence of other symptoms, these measures are usually sufficient. I invite you to apply them and only monitor the situation. If the lesions persist for more than 7 days without improvement, I suggest consulting a doctor as a precaution.
I hope I've been helpful, I remain available if you have any further questions!
Tom Samaha, pharmacist