I've Had This Bump On My Head For At Least

I've had this bump on my head for at least two weeks. I did get hit in the head by the locker above me one day but, it was minor. it doesn't hurt when you touch it and is hard. I haven't been having more headaches than usual, or have felt very nauseous. I had a 24 hour stomach flu a couple days ago but, it went away. Help?