1month old baby fell on the bed

I’m asking for a friend. Her baby just turned 1 month old lastweek, the baby fell on the bed and experiencing fever after. She live in third world country, the hospital will only take or entertain you when you only have money. She took him to the public hospital and the doctor just gave her antibiotic without explanation and let her go. I was wondering why did the doctor gave the baby an antibiotic when the fever is only 100.4.? What is your opinion mommies?