If its respitory infection raise your temps a few degrees higher than normal, keep the cage dry and clean, and avoid stressing it. It doesn't sound like mouth rot because it ussually has a white cheesy juicy look, and scabs form. It may have just pushed its snout into something trying to hide. Make sure it has good hide spots.
Make sure it has clean water. What do you use for substrate? Avoid cedar or pine because the fumes & sap are toxic. If it doesn't respond to this and it gets weak you need to get it to a vet who deals with reptiles.
You mentioned your cage being too hot. This can cause reptiles to breathe through an open mouth as they are trying to cool down internally. Keep your temps between 70 and 88. The best thing to use is a under tank heat pad under half the cage so the snake can thermoregulate its temp.
Good luck,
Jaremy