4 month old has the Flu.

Went to the ER yesterday and found out my baby girl has the flu. ☹️ We went to her pediatricians office twice and she was misdiagnosed. I noticed last night before we gave her the medicine that she started to feel a little better. she was playing with her toys and smiling. We’ve been giving her Tylenol and her fever has gone down. The doctor prescribed her Tami Flu and we gave it to her last night but she vomited it up. I know vomiting is a side effect but is it normal to vomit it up after? The Pharmacist told us that she has to eat something solid with it but we haven’t started her on baby food yet. She’s still on breastmilk.