My brother's guineapig of 3 and a half recently passed away from phemonia and we've heard it could pass of to the other piggy so we went to the vets to get him checked out and he's fine.And today we got a new 6week old male guineapig to replace him but at the moment he is not moving,eating or drinking and were not sure how to introduce them to eachother because we don't want them to fight or argue is there any ways to make it as easy as possible?