Is it possible to just wake up with bronchitis one day? my son woke up with a cough 2 days ago. no other symptoms until yesterday. runny nose now too.

Likely virus: Many youngsters get respiratory viruses suddenly. They are well and then suddenly start to cough. "bronchtis" is the term usually used for a wet cough. Fever and runny nose can also come with the cough. It should be done in 3 - 5 days. If he gets a lot worse or it lasts longer, call your doctor. Keep fluids going and be generous with tylenol (acetaminophen) or Ibuprofen to make him more comfortable.