Your baby is young. Even in an adult, Bronchitis can be very serious...
If one antibiotic does not work, then yes, another family of Antibiotics has to be prescribed.
Next, you need to make sure it does not get worse... or it can damage the lungs.
I had Bronchitis once... it got worse, and turned into Pneumonia.
So be careful....
If you are breastfeeding, keep doing that ON-demand, 24/7, day and night."Food" or solids is not a baby's primary source of nutrition at this age... breastmilk is.
For the 1st year of life... a baby needs to be fed on-demand breastmilk or Formula if that is what you are using.
NOT solids and not other liquids.
She is so young, and if you start giving her solids willy nilly and instead of nursing.. then your milk supply will also diminish... and you do not want that to happen. Breastfeeding or Formula... should be her PRIMARY source of intake. NOT solids.
Bronchitis is either bacterial or viral. And it requires medicine.
My Mom had Bronchitis once, and she didn't go to the doctor right away thinking eating healthy will be good enough. Well it got worse. She finally went to the Doctor and she got lung damage... permanently now.
all the best,