Neck Rash

I could use some opinions! I just noticed this rash that popped up on my little guys neck. I’m assuming it’s from spit-up and drooling- both of which he does a lot of. Just making sure it doesn’t seem to y’all like something I need to take him in for...it doesn’t seem to bother him at all. TIA!

Also, I have had eczema since I was little and this is not eczema. Nor is it raised bumps at all just redness. He’s just at 12 weeks if that makes a difference. Thanks again!!