What's this mark on my baby's cheeks?

This is usually cause by the dirt, heat, etc. need to keep it clean. For fast recovery, u may need to use those mild steroid cream. After 1-2 days of application, it'll gone very fast and can use normal cream to maintain and keep it clean. Urs is small case, my girl has it on both of her cheeks and are big patches, and those bm or watever normal cream took too long to heal, hence i have to use those mild steroid cream to cure it. If not u can use Ezerra. It's very good for this situation too.