How do i return a sick mouse to petco?

So I got a mouse from petco yesterday to put with the 2 i already have and ive been keeping a close eye on her. She gets along well with the other 2 and she seems to be eating and drinking fine, but her breathing is rattly and she sneezes quite a bit, so im thinking she has a respiratory infection (i could be wrong) The store has a 14 day return policy but im curious if they would treat her and let me take her back, or if i would just have to get another mouse? And should i call first or just take her in and explain whats going on?

Love my Newf

Why the hell do you keep posting this????? Just TAKE IT BACK. But expect your other mice to DIE since you stupidly stuck it in with them without quarantining it from the others for at least several days.