Bumps on belly and back

Hello, can someone tell me what this could be? I had taken him to the hospital Saturday for a fever and they told me he was fine, he tested negative for flu and Covid and that I should just give him Tylenol and a warm bath. Sunday he was fine and this morning he woke up with these rash like bumps on his stomach and back...

Excuse his mouth he has just woke up and that’s dry milk from his bottle.

I took him a bath and he stills has some. He’s a bit fussy and his pediatrician doesn’t have an openings until Wednesday :\