So, I'm a new rat owner, got my two boys a week ago from a local petstore. One of them has been sneezing from day one. I changed the bedding I was using, and that didn't help much. Well, yesterday he started coughing, and today he woke up breathing heavily and with porphyrin around his nose. He is going to the vet tomorrow, but in the last 12 hours or so his condition seems to have declined drastically. He is lethargic, breathing shallow, and can't seem to get comfortable. My question is, what is the general timeline of a respiratory infection? I'm kicking myself for not catching this earlier, and I'm so worried that he won't last the night, or long enough for the antibiotics to take effect.