Again fever and cough after 22 days.

My daughter is three and a half years old. She suddenly had some cough around the 27th, though for two–four days before that she had a little cough. But on the 27th the cough increased. She was otherwise very active and went to sleep after playing. Suddenly, when we checked her, she had a fever of 100°F. We gave her medicine, but by morning the fever rose to 102–103°F along with more cough. The cough was so much that at first we gave a full course of Paediatric Amoxicillin (Ponz Gen Amoxy) for the fever. That course got completed. After that we stopped the medicine, thinking that the cough would settle on its own. But it didn’t. So we showed her to the doctor again. He checked and said the chest was clear, and that now she was fine. She stayed okay for 2–3 days, but after that she continued to have mild cough on and off. It has not even been a full month since then, and now, around 22–23 days later, she again developed fever suddenly. At night, after playing well, she went to sleepand then suddenly had a fever of about 101°F along with cough.r And this time the cough sounds like a dog barking. Why is this happening — why is she falling sick again so quickly like this