Memory loss , pain in back brain. Pycho?

Sir, i m 19 yrs old .As soon as my age is increasing ,my sufferings about memory are increasing so much. From last 2-3 yr, i feel mental problems are incresing fast. even, now the condition is that i am unable to remember which class, topics were going last time(yesterday).From last 1 year i also start to feel pain as streching in back & other portion of head when i try to remember (focus) some learnings. Now, in b/w persons I find myself unable to use the language,words,facts,knowledge which i have gone through in last 2-3 yrs very well . i get myself unconfident in putting any small fact,however i already studied it many times. each time i feel myself nervous and doutful on mostly topics which are very simple .plz i also want to be confident as my other friends and live commonly like others.A pshycology doctor said me that it's ur pshyco but "is my day-night labour.intrest for study also my pycho ? i can not bear my life such way" PLZ help me & suggest me apropriate advice.