What to do for a child with bronchitis, off and on fever, and coughing?

See doctor. Bronchitis is almost always a viral infection, although children can have pertussis (whooping cough). Fever may occur with this. If, however, the fever is quite high, the character of the sputum is changing or looks like pus, the child is having problems breathing, or is otherwise worsening, then a visit to your doctor would be a good idea.