Does anyone know what this is on my baby? 🙄

💕m

Should I contact my pedi or dermatologist to see what this is? I’m not sure if he was born with it as I can’t really remember but I do know it has been there for months now & he is about to be 5 months old in like a week. My fiancé seems to think it’s a mole but I’m not too sure. Anyone have ideas what it is or what I should do? Thank you!