My mouse Lila is around 2 months old. She's been sneezing a lot even before she was introduced to the substrate that she's on, which is megazorb and paper tissue in a sputnik to nest in. She's now back at home from the vet. She was climbing upside down in her carry case, was acting energetic for the vet and her breathing sounded ok. She has shiny fur, healthy eyes, is eating and drinking fine. At home she doesn't explore or play as much as other mice do though. The vet didn't give anything at all for her to take. She said it's probably viral and not a respiratory infection. I'm not sure what the difference is between the two? Should she have been given something?