I am Suffering From a huge attention problem

First,i am sorry about my poor English because i am a foreigner and found this site while i was searching for information about my problem.
Let me explain my situation
I am a student studying at the university at English Preparatory Program,and I am going to take lectures related to my department following academic year.I didn't have such a problem before last december.The problem i will tell you about now might sound so strange and funny because when i look at myself from another person's perspective,i feel like crazy.I finished the first term as the student who got the best grade among approximately 500 students,about 100 of whom are at my level,intermediate.However,i can't study now as effectively as the first term,in other words,i have a kind of phobia preventing me from studying even over a few hours.I had been capable of studying for hours without any pause until the last december.The problem is that i am conditioned that when i start studying,distractions will prevent me from studying.It could be anything.For example,a normal student gets his/her materials such as dictionary,eraser,books and other required ones like these,and when s/he starts studying,s/he doesn't think about those.S/he just concentrates on the article s/he has to study.However,when i start studying,my mind begins to think and worry about them inevitably,and i can't stop that.It's like somebody whispers something like "the eraser is laid just there and you can't study due to this" my ears.I don't experience this situations only during studying at home or library,but also in the class and during exams.For instance,during an exam,after the instructor distributes the papers,my mind begins to deal with the eraser laying near my hand,or during classes,instead of focusing on what the instructor tells,my mind copes with the eraser laying near the notebook,so i can't concentrate as well as i used to,which makes me feel very anxious and depressive.
There are no enough words to tell how it makes a student feel to lose ability to study,especially for a top student.Until 4 months ago,i was sure that if i continue studying as hard as i used to,i was going to be admitted to one of the top universities in the world after graduation.Everyone i told about my targets agreed that i could succeed what i used to desire.Now,i am thinking about leaving the school and doing a job that doesn't require improved academic skills such as waiter or footboy
I used to spend my most time studying last term,but these days,after returning from the school,i sleep almost three hours a day to kill time,and after dinner,i do my homework and kill time again on the computer,which makes me look so lazy.
I saw a psychiatrist 2 months ago.He analysed me,and decided i was depressed because of some bad incidents i had experienced.He said just give yourself some time,it will go away.He didn't think i needed to take medicine,so he didn't prescribe anything.However,troubles still exist like what they were and i don't think i can take it anymore.
I really don't know what happened to me and what kind of a mental disease it is.Life hasn't been very hard for me so far...

I agree that it sounds like depression. I think you might be feeling a lot of stress over doing well and you're sort of falling apart as a result. I would go back to the doctor and say that you are not doing better--in fact, things are getting worse. Some people do need medicine to help them. Also, is there someone at your school, like a counselor or a therapist, you can talk to?

I guess it's possible you have some ADD, but you would need more testing with a professional to confirm it. However, the fact that you have done so well before makes me wonder about that diagnosis.

Let us know how things are going!

I checked and the agreement is that ADD/ADHD does not just suddenly develop in adulthood.

ADD usually works the opposite sometimes. It is there in childhood there are signs and it can go away as one grows older and you will grow out of it. But as far as it just appearing. You do no grow into it ADD. The signs are there at a young age and sometimes will go away as we age.

Sometimes ADD symptoms can be present due to our environment. We are the product of our environment and we live in a technologically advanced society that moves at a very rapid pace. Therefore people sometimes think they can be ADD because the symptoms present themselves. But sometimes it can be could be known as pseudo ADD.
Or if a class or lecture is boring and uninteresting it could cause loss of focus or interest.

Also you mention you were the top student. It could be causing your feeling of anxiety or depression and you do not feel if you do not have everything right you many not be the best in the class again. You have such a high pedestal now and are feeling the pressure and stress to perform again. That you have to shoot for the stars. So you are developing different coping skills to try and deal with the pressure. Something that takes you mind off it and gives you temporary relief.

It could be depression as was mentioned or anxiety. Maybe try talking to a school counselor see if they can help you out or maybe try to see a psychologist or psychiatrist to try and get to the root of the problem.

--Maus5321

Thanks for the each answer friends.