Don't feel pain

Ive spent so long feeling pain that ive numbed to it. It seems that only when i really hurt i ever feeling anything. My grandmother is on her death bed and doesn't have much longer and i feel as though i need to do something to myself to feel anything. Everyone around me is feeling the pain of her loss and i dont feel anything. I dont feel human. I burnt myself with my cigarette to try and feel the pain but its not enough. I dont understand why i cant let my emotions go and just grieve like everyone else but i stay so bottled up, its torture. I want to just feel the pain and let it go. all i can think about it trying to force myself to feel the pain of those around me. I dont know what is wrong me me...