wondering!?

Amber • 2️⃣5️⃣years old: April 22, 1992🎂. 💋Mom: June 8, 2017👶🏼. 👰🏼Married: January 16, 2013💍. 👼🏼I believe in God🙏🏼.
What can this be on my son face. He is going to be one month old on Saturday. Can it be a heat rash or can it be his milk?