My baby is 1 month and 15 days old, he has small blisters on his back near his thighs, what are the reasons?

A. Currently you can use calamine lotion or candidate dusting powder without an assessment it would be difficult to say why it is happening I hope you’re not using diapers all 24 x 7 as that can also be reason if that’s not the situation then maybe some allergy or infection that is developing