How can I come out of my imaginary game of parallel universe?

Hello doctor,

I am suffering from a strange problem. I have played an imaginary game. In the imagination, I had created a parallel universe. I was the head of my country and made the rules. I added the experiences of real life in that game. When I was alone, I played the role of different people like sometimes I assumed myself as a teacher of some school of my country and played as if I am teaching the students. Whenever I got time, I played the game. One of my real friends was also a member of my imaginary world. Sometimes I played with him and sometimes alone. I have also created some festival of my world and celebrate it. I had created many institutions in my world. My universe was not fully detailed or written, but it just exists in my mind. But, I left this game three years ago, and now I am 18 years. But I do not find myself comfortable in the real world. My two personality is now creating conflict in the real world. My academic performance is being degraded. I often have a headache. I look very normal. I understand my responsibilities as well. I do not look abnormal from any angle. My friend and family do not know that I am suffering from. But, I am suffering from an inner conflict of my identity. My fantasy game has affected my sense of perception. So my question is when I know very well that my world was my imagination and nothing else, then why am I still suffering? Will the problem be solved without treatment when I grow up?