It sounds like either a respiratory infection, or possibly cardiac issues. Are her feet, tail tip, ears, gums still pink? A tiny bit of pure dark chocolate can help as a natural bronchodilator, but often they don't want to eat when they're distressed. Other than the advice above, keep her comfortable and, if possible see that she eats a bit for energy/moisture until you can get her to the vet. She needs to go onto a good antibiotic combo like doxy/baytril or zithro, and, depending upon how advanced the URI might be, possibly a steroid like prednisone to reduce inflammation. If you have any eucaplytus oil or Vicks vaporub, you can put a bit in a bowl of hot water and set it in the room; don't put it too close to the rat, but just in the room where the vapors can help open airways. Sending healing vibes to your little one until you can get to the vet's tomorrow.