Why do I Keep hearing a voice telling me to let my feeling out?

I am not really a happy teenager girl. Most of my school friends thinks I am because I pretend to show them that I am happy person but I am not. I don`t get alone with my families. I am a teenager girl that hide her feeling ad her emotion from every one. only 3 of my friends know. every morning I wake up sad ,mad .angry,depress and some tear come out of my eye but clear it out. last night and today stared to heard a voice telling to let my feeling out and then I start cry unexpectedly and I cant stop because I hide many feeling inside of me and I try not show it. . Some of my teachers and friends notice me crying and ask me what wrong or if I am okay and I am tell them I am fine but when I am not.
should I listen to strange voice telling me let my feeling out but I don't really know where is that strange voice coming from.
please answer this question as soon and fat as possible.

That is probably your inner feelings telling you what you need to do, tell your friends how you feel, and maybe even your teachers. Dont hold yourself prisoner to your emotions, be you. Because their is only one of you. If you feel as if your life is empty, maybe you need to look at yourself, find a hobby, talk to your friends more, maybe even find a religion.:)