How long am I going to be like this? in Maze of my mind

I feel exhausted and tired all the time, the only time I ever smile or laugh is when I am watching my phone, and if I put it down I once again start feeling the dread of anxiety creeping up on me, look at me I was a smart kid, bright and intelligent and honest and a well wisher, now I am reduced to nothing. I am going to be giving the an important exam tonight and I am not prepared, If I pray for a miracle I know it’s like asking to cheat out and not do the hard work for success, but I desperately need a miracle at this point any miracle just to get this stress out of my head I am mentally soo tried I can’t even hold conversations about my academics with my own friend. I prefer to shut off and isolate myself and that is what I am going to do. Please I am on the edge of crying and breaking down these days, so on one hand I would be happy that everything is over and I can breathe again but on other hand I would have lost my chance of becoming a doctor
My parents put in so much effort for me, I am sorry