Thanks for your replies !
My guinea pig got sick in October, so, I don't think he could have gone to my hamster
He eats, drinks, plays, like any hamster
(but he is my first hammy so...)
Maybe it would be interesting to note that he is a rescued hamster, he was found 1.5 month ago in a hole of a basement's wall, so, a girl I know from a guinea pig forum got him, and tried to find him a home : he arrived here
He has got corn litter, with wood shaving on the top (hope I make myself understand lol), but those wood shaving are supposed to be horse bedding, they sell it in big package (like 25 kg, I think), and they are dust-free (that's weird, by the way, that bedding for big animals is dust free, while it isn't for small animals) Anyway, I don't think that's why he sneezes
I really think it's, for him, a way of communication, as he doesn't do it all the time, not even everyday, but there are moments when he sneezes, for, maybe 10-15 minutes sometimes, sometimes it is just one or two sneezing, it depends, and it's more like if he coughed, there are some "coughing fits", but with sneezing, not coughing
I really hope I make myself understood, that's quite difficult for me, I still don't have any dictionnary near me (and I'm French
)