What is wrong with my arm (please answer)?

today around lunchtime as i was going to the changing rooms i fell on to paving slabs and cut i knees i didnt think much of it untill i was getting changed from p.e (gym) when i suddenly felt as if every thing was moving around me and my friend said i went really pale we told the teacher yet she did nothing then a couple of minuites later i mean my arm was always slightly hurting but i thoughtthis a was goin to fade away my arm was like ago y after i picked up my gym bag so all after noom i have been in this pain as i got home u put my arm in a sling made with a scarf which slightly eased the pain but it stl hurts what should i doplease amswer in in soo much pain and im only 11