what this be it doesn't bother my son

That looks like a heat rash

he doesn't get diaper rashes and it's not his wipeys unless he gets it when we carry him But I dont know I was thinking of changing his diapers

I'm not sure what it is, but I remember with my son it was always been difficult to keep that area clean dirt and moisture would get stuck under there that could be causing the rash

its like a yeast infection my daughter had it on her neck amd she had it there i just used corn startch an it goes away

Put some corn starch on it, it look like it's a moisture rash from the diaper

I always used to put a little baby powder in spots like thae