My Daughter Was Sick With The Basic Flu Two Days

My daughter was sick with the basic flu two days ago (runny nose,fever and a tiny cough) shes only 5mnths old. Although today she has slept most of it and i have been trying to get her to breast feed properally she still manages to have an up and down fever and heart rate within seconds should i be panicking as much as i am as she is my first and only child.