strawberry mark or rash??

My first son had a strawberry mark that was on his back. He’s 3.5 now and still has it. This is my 2 month old and I don’t remember if this is how it started out with my first or if this could be something else. I didn’t notice until now because he has a lot of hair on the back of his head. Kinda worried. We have an appointment on March 9th for his well check, should I wait until then to bring it up or?

Sorry I can’t get a good picture.