Blisters on 16 month old - diaper rash??

Kat • IVF baby born 12.5.19 after: 2 years, 1 ectopic, 4 IUIs, 2 rounds of IVF & 3 embryo transfers!! 💕 Baby #2 (surprise!) due 6.2021

I’ve never seen these blisters on my son before, and they showed up out of nowhere right after a bath (we didn’t use any new products in the bath). Daycare always puts his diapers on SO tight, so thinking that could possibly have something to do with it? We put a bunch of diaper cream on him, but still trying to figure out what could’ve caused this in the first place. Anyone experience this before?