Dont know if my finger is sprained or broken ?!

Yesterday i was playing Football in Gym and the football was really high, when i went to jump for it the ball hit my index finger and bent it back, it was really swolen and red, but today its the same color as all my other fingers and its only about 3 milimeters swollen then my other fingers, i can move it like any other of my fingers except straighten it all the way and bend it down all the way, if i move the finger i can move it with no or tiny bit of pain but if i move it all the way straight or bent its like someone is pinching me lightly. Is it broken or sprained.? also just my knuckles are a little bit purple, like a really really faded purple, almost cant tell unless you look closely, the knuckles on my finger, not the knuckles that you punch with on your handHealth Question & Answer

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