My 3 Month Old Has These Red Pimples That Form

My 3 month old has these red pimples that form pus and then crust yellow on his scalp. He has this from when he was only a few weeks old. It seems to be itchy for him.
He also has a red tan on his face and down his shoulder and arm. Everything is on the right side of his body.
Could you please help us! !♡