NEED ADVICE: red dots on face and body

So my baby was getting over a fever, he had his lunch and while he was napping he suddenly got red dots all over his face, cheek, neck, and body. It doesn’t itch and nothing is swollen, he doesn’t seem hot, but he’s very sleepy and doesn’t want to drink water or milk as much as he used to.

It might be a food reaction? The red spots aren’t swollen or look itchy, and it’s not hot out so it can’t be a heat rash. I’m not sure what’s happening and I’ve given him a bath, changed his clothes and diaper, gave him milk and I’m not sure what to do next. I can’t go to his pediatrician since it’s closed but I will go tomorrow. Any idea what this is?

Please no hate I’m a FTM and I’ve done everything I can. Just asking if this has happened to anyone else’s baby