What happen to my hair?!?

When i was in 5th grade i had awesome straight hair! i grew it until it reached my shoulders! Then in 6th grade i cut it so i can spike it up. When i was in 7th grade my hair started being curly and nappy! Im talking about cow licks everywhere and its so unmanageable. When i spike it up it looks like a Afro! Im in 8th grade now and still has the same problem! Can anyone explain this? And how do you put it back?