What is this?

Hello mommies. My LO has this marks on his arms, legs and chest. He doesn’t scratch on any of this marks or any part of his body for that matter. What is this? Im worried. Should i change his shampoo/body wash? Is this due to dryness? Ive applied Mustela facial cream moisturiser for a week now but the marks are still there. Ive tried applying Johnson Baby oil, still no change. My son is 4 months old. And formula-fed. #firstbaby #advicepls