Will anyone answer this?

i am considered by everyone around me as intelligent and i have scored this really good rank in two entrance exams that i took after my 12th std.but the problem is -people think i work really hard so that i can learn a lot.but the thing is i work hard coz i often dont remember what i learned.its like i study the same subject 4-5 times and then i tend to forget it after a few weeks.i am okay about things that i understand but things like Anatomy-i feel i am going to be a big flop !(i have just started my M.B.B.S course)i just cant remember it at all !and from past two years i feel i dont concentrate the way i used to when i was in high school.from past few months ,when i am in the cl i just go blank and its as if the teacher and i are separated by soundproof wall.and at times i listen well.god knows what i was thinking all the time i was blank coz i really am not able to recollect it well.and another big problem is-when a teacher says something important, i try very hard to remember it well then and there but then bham!the next min i struggle to remember what i was trying to memorise.it doesnt happen all the time but more often than not.i was not this way before.this is making me depressed coz i am in a medical college and i need to be competent.just because i do well in exams( i have done well in my first internals here)doesnt mean there is nothing wrong with me.as i said my IQ is good enough and i do nothing but toil all day so its nothing great if i do well.and another thing is -when a person starts speaking to me i never hear him or her the first time.this happens 98 out of 100 times.the person has to repeat things to make me tune my brain to what they are telling.once i start listening then i listen well.also i am over imaginative as in the good sense (i mean i dont imagine killing people or anything of that magnitude just because i dont want to .i can always imagine anything ,i myself can create a situation in my mind and play it like a movie with audio )and am not easily frightened by scenes of violence -is all this NORMAL?