PLEASE ADVISE ME PLEASE AM ON VERY DANGER?!

hi friends
could you please advise me i have a very strange problem , which i have been facing it since Dec.2004.

when i was graduation Final year in 2004, i used to sit in the class room in the first row i.e before the lecturer .ok it is good
but.... the problem has started at this time ONLY......i am really sad on it and no doubt i am cleverer in the class room.
one day i got suddenly one thought if i got cough then some then some of small drops may fall on the lecturer from my mouth ( as he is just one meter to as i used to sit in the front bench)
so i got fear day by day of course i did not have cough.
i get more fear and it converted into a danger one....that is if am going to split on the lecturer while the class is going on.....STOPPED MY MIND .....i got shivering in me and i do not understand why this is happening to me. ( i think it was because of ,i generally give lot of respect to the lecturer)

From the next day onwards i used to sit in third bench and my friends had asked me why you are sitting in third line bench though i have place in the first line in front of lecturer and i did not said to my friends my problem

days passed and my fear is also increased i.e ( if i unconsciously may spit on the lecturer face) so i sat on the last bench and felt very anxiety to complete the class. then my education standard had
gradually became dull student. because MY PROBLEM IS VERY STRANGE I DO NOT KNOW WHY IT WAS DEVELOPED IN ME.
like that i have completed the classes at least 4 months.

now in 2011.....i decided to do a professional course to increase my qualification and recently i joined an academic institute .

for the first one week i went to the classes very good and SUDDENLY I REMEMBERED MY GRADUATION SITUATION IN 2004. then suddenly i became PANIC it means i got very fear now also.

MY SUB CONSCIOUS MIND IS WARNING ME AND A I AM GETTING AFRAID THAT ( I MAY SPITE ON THE LECTURER UNCONSCIOUSLY) SO I AM GETTING VERY FEAR.

BUT I KNOW IT IS ALL MY FEAR BUT WHY I AM GETTING THIS FEAR I DO NOT UNDERSTAND AND ( I HAVE TO SIT IN THE CLASS AT LEAST 6 - 7 HOURS A DAY BUT I AM FACING A LOT OF INTERNAL TROUBLE AND GETTING SWET AND ANXIETY.

EVEN AFTER THE CLASS I AM THINKING THE SAME ( I KNOW IT IS ALL MY ILLUSION THINKING)

BUT HOW CAN I OVER COME THIS PROBLEM ?? EVEN NOW ALSO I AM SITING AT THE LAST BENCH AND GETTING FEAR NOT WITH ONE LECTURER BUT WITH ALL LECTURERS
I HAVE TO ATTEND THE CLASSES TO PASS MY EXAMS AND I AM NOT A CHILD TO SAY IT TO ONE OF MY FRIEND ABOUT MY PROBLEM TO GET SOLUTION ( AM THINKING IF I SAY IT TO HIM HE MAY GET THIS KIND OF PROBLEM FOR HIM ) SO WHAT I HAVE TO DO PLEASE SUGGEST ME.

THANK YOU
RMSDT