How long has it been since you were seen by your doctor?
If you feel you cant wait until office hours, go to an urgent care clinic or ER to get a breathing treatment and get checked that it hasn't developed into pneumonia.
If you can wait, call your doctor's office when open and speak to his/her nurse to tell them how you are feeling and ask to see the doctor immediately.
We aren't medical professionals, all we can do is urge you to seek medical attention as soon as possible. Either way, you might want to alert a friend or neighbor and ask them to check on your well being in the morning in case you need to get yourself to a doctor.