Dwarf Campbells male making squeaking sounds?

[rainbowdynasty]

Hello, this is my first time posting here. I've been using this site for advice since I got my first hamster, Pasha, in April of 2017. He has since passed, but I have a new hamster, Ash, who I'm worried about.

I've had Ash for about 4 months now, and just this morning I noticed that he was making a strange squeaking noise. He's never done this before today, that I've heard, and it's caught me off guard. I read that it could be a sign of a respiratory infection, or that it could just be that he's happy (though he is often very grumpy during the day).

Just as some additional info, we also have four male rats who squeak and chatter constantly. We have no female rodents in the house (that we know of, we have had mice recently but they haven't been anywhere near the pets). The pets are all kept nearby each other.

I'm just worried that he might be getting sick, and I can't take him to the vet until Thursday. If anyone has dealt with a similar situation, or has some advice to a worried ham owner, it'd be much appreciated <3