Help me

The final year of my college life seems to have induced a lots of changes in me.These are becoming obviously visible to me.
First my eating habits have taken an u turn.Never do i feel like eating and i dont remember an instant in the recent past when ive felt hunger.Its been months since i have sat down for a perfect meal and my plate stares longingly at me when I finish my meals with bowls and cups.
The second useful thing I used to do earlier was to sleep well and even sleep seems to elude me now.A person (me) who used to go to bed at 9.30pm sharp and get up at 4 am precise ,now tries to sleep by 2 am and gets up at 5...
The third most critical is my state of mind...it seems to be happy always..happy without any particular reason.Am laughing alone like someone being tickled by a ghost.There have been many critical situations and matters of concern in the past few days...still nothing seems to have worried me..
Donno why my attitude has changed...