Wanting to know what this could be?

my 2 month old has tiny bump around his neck area and some on his back and shoulders. Is this excema, or acne. or a rash? im going to have him checked out tomrrow. Hes also spitting up the similac advance milk i give him, its hard ot say if its normal or not because its moderate spitting up. I dont know if i should have them switch it or not. i do burp ihm after feedings and i dont lay him down right away.