New Rats, Sneezing, Please Advise

Hi, I know about Rat respiratory issues because I've owned rats in the past, but this new rat I have is a very confusing sneezer. I adopted two neutered boys five days ago, and the first day I brought them home, William, started sneezing A LOT, I mean, like every ten seconds. He did this for the whole first day except when he layed down, at which point he was completely silent. By the second day he was still sneezing quite a bit, but not nearly as much, and again it was only while he was being active.

The sneezing has progressively improved, but still today, his fifth day here, he has sneezing fits. There are times when he sneezes very frequently, but then there are hours on end that he doesn't sneeze at all. He never sneezes when he's being still, only when he's active, but not every time he's active.

I use(d) aspen wood shavings, but changed their bedding to carefresh just in case he's a bit hyper-sensitive. I'm just confused... He came from a VERY responsible rat rescue, from a cage full of his brothers. He lives with his brother in quarantine now, and his brother is fine. Other than the sneezing (and the fact that he is a bit shyer than his brother, Walter), he seems fine. His nose is not runny, his eyes are bright and clear and red-stuff free, his poop is normal, his appetite is healthy, and his breathing is fine outside of the sneezing.... and he does seem to sneeze more when he's excited or stressed, or both.

So i'm just wondering if he's maybe just got a touchy nose, or if he's still adjusting, or if i should bring him to a vet. I don't have a problem bringing him to the vet, and will if i need to. But the rat-experienced vets around here are quite expensive, with a minimum of 45$ just to look at him. So if it's just an adjustment or personality issue, I'd rather hold off; but at the same time, I don't want him to suffer from any lung damage if it is in fact a respiratory infection.

Any advice/insight would be greatly appreciated...