[Shayna&Liam]

Rats have very delicate respiratory systems and because of that are prone to fits of sneezing, and colds, etc. My first question is, do you have him in a glass or wire cage? Glass restricts the airflow and may make your rattie more prone to sneezing fits. Also, did the tank he was in at the pet store have wood shavings? Shavings are very dusty in comparison to the Carefresh Paper Bedding; my thought is that maybe he was fairly adjusted to the shavings, and the very lack of dust in the Carefresh is what's making him sneeze now.

I'm not an expert though so hopefully someone else has better ideas?

 

[Shayna&Liam]

Sounds like you're doing everything right, good for you. I agree that you should get the rat at the petstore that Archie was cuddling up to, they are already bonded and it would be easier than introducing him to a new rat. If they don't take to each other, you will be stuck with two rats in two separate cages, don't forget - and two cages means twice the cleaning, and space taken up.

There is a kind of Carefresh, I don't know what it's called actually (funny enough since it's what I use with the girls) but it's multicolored, made from recycled paper and virtually dust free. It looks like confetti, it's really easy to dig and nest in, and it absorbs pee smell a lot better than anything else I have used.

Here is a good tool when selecting a good cage for your rats:

http://www.rattycorner.com/odds/calc.shtml

I'm sure there are many ratty calculators and maybe somebody knows one that is more accurate, but it's a good guideline anyways. Definitely get Archie out of the hamster cage as soon as possible.

P.S. He's very cute.