Why is this happening to me?

Sorry about your dad...Anyways 3 months is a short time, its understandable that you're still mourning over him being gone, but you cant do anything to bring him back. My advise is think of what your dad would tell you right now. He'd want you to keep on living your life and be as succesful as you can, I'm sure. Only you can pull yourself out of this one and you will.