Actually i dont know wht it is. It is. ?

I m 16 yrs old nd i hve no concentration in class whn teacher teaches i listen evrythng bt meanwhile if sm1 asks i doesnt answer nd after tht i frget evrythng nt only in studies bt also i hvnt remeber any thing whch has been hppnd 1or 2yrs before or of my chldhood. I awake late night nt because i want to ,i try to sleep bt i cant nd next day i dont fall asleep in day time....nd whn smtime i fall asleep in daytime if any1 tries to wake up me i cant.....nd i smtime feel vry different like sad bt wthout any reason nd feel irritated nd smtimes i hve to much anger bt i never tell a word to tht prsn who make me angry instead of tht i hurt myslf....i cut my hand or cry.i hve no breakups or any prsn in life tht i will be sad bt i get sad nd thn get disturb fr 1 or 2 days. Whnever i sit to study i start thnking smthng else nd got diverted nd thatsy i m weak in studies nd if i smtime concentrate thn i get remember evrythng. I smtime cant evn do small calculations. So plz tell me wht it is....?