That is a birth mark. It’s called a stork bite. It’s nothing harmful. Here’s an article about it. Don’t worry mama, it will go away in time. Your baby is fine and healthy 100%. Pray about your anxiety!
Edge of scalp is a common spot for eczema. Try different products- her shampoo, detergent etc
Could be heat rash
Our Ped said just keep moisturizing. It's from being in their back so much
I just put ointment on it
Google it it’s normal unless it looks irritated, called the storks mark