You explode with anger! Your claws tear at the walls in fury! You slam your entire weight against the closed and locked door. Your fury goes on for what seems like hours, but could only be minutes, or maybe days, time doesn't mean much to you right now. Your mind scream obscenities at first, then it just screams, finally you let out a terrific roar that echos your own thoughts entirely.
You pause from your rage and try to think of a plan, but you find you can't remember the English words you once knew. You try harder, but the words won't come. This frustrates you and you let out a snarl, and then a roar. You now can't remember why you were angry, something was taken from you, but you can't remember what. You're tired and slowly fall asleep.
When you wake up you're human mind has slipped away completely.