What Does Severe Fatigue With Headache After Being Hit On Head Suggest?

My son has been tired yesterday and especially today. He has a headache and temp of 100.8. Today. My other son said he got hit with a football yesterday on top of his head, I just found that out. He is 3 as of September 8. He and I both had a terrible sickness , it's gone now but lasted for 2 weeks. 103 fever for days. He got better before me . We got antibiotics for it. I am very worried!