Baby rash

Karla • 26. Married. Momma to 2 baby girls ❤️
My baby is 3 months. And she keeps getting this rash like little red bumps on her face. Almost looks like little white pimples. Mostly on cheeks and some on forehead. And it just comes and goes. Even within an hour or so. It's so weird idk if it's just the cold weather or blankets?  I have no idea. Idk if i should call her doctor?? Idk what to do. I don't wanna worry if it's normal... Is it?..