I was running, and someone pushed me (this was at school), and I feel down and h!

I was running, and someone pushed me (this was at school), and I feel down and hit my head really hard...?

...giving me a horrible headache, and now the headache is gone, but my arm hurts like heck. Strangely, it wasn't the arm that I fell on, but the pain is getting worse. Any suggestions as to what it might be?

There are many "possibilities" as to what it might be. You most definitely should let your Dr. know about what happened and what you have experienced. Sometimes, with a head injury, you could develop a bleed inside your skull. And, this problem can get much worse as a few days go by. Obtaining a CT scan or even an MRI would be recommended, especially with having the headache and the neurological symptoms you decribe (pain in your arm). If you do not have a Dr. a trip to the Emergency Room might be you safest thing. Even if you have to wait in the ER and the scans come out normal (which is the best outcome and one you hope happens), I would still recommend it. Because, the alternative could be life threatening. I don't want to scare you but, if it were me or my family member, I would definitely get them check out immediately. Take care and good luck with this.