I don't know why

I don't know why am i thinking alot..
I don't know why am i only think of those sad days we had..
I don't know why am i thinking of sad days instead of the happy ones..
I really don't know why am i acting like that nowadays..
I have forgotten when is our happy days..
Izzit months ago or just weeks ago or either days ago..?
Do i really have problem.?
Do i think to much already.?
Why am i like that.?
Help..!