2 Year Old has fever for 4 days now, will he be okay?

My 2 year-old has had a fever not exceeding 101.8 degrees along with a congested cough, runny nose, lack of appetite, fighting off dehydration, and hardly any energy. He's sleeping a lot or laying there totally out of it. Today is day 4, he went to the doctor who tested him for flu and said it was negative and to come back in 3 days if he wasn't better. Is this normal? Will he be okay? He's only been sick once before and he's my first so maybe I'm overreacting?