At a loss

I should be studying right now, but I can't seem to focus.
What is going on. I need to write a paper as well.
All this stuff is crashing down on me.

I am ecstatic one minute for a friend of mine who is finding his way to Christ.
Than the next I'm back down on the ground feeling crushed by these stupid feelings that won't go away.
God is answering my prayers in real tangible ways...
and then I am feeling all alone.
I don't get it. Those two things are opposites.
Why can't I trust Him, I know He is real and true and wants what is best for me. So why am I not trusting?
Why do these tears come so often. I want them to stop. I don't want to cry anymore about this.
I just don't know what to do.
I want to stop hurting, but not stop feeling. How?

I am so happy some days, so full of real joy.
and then a day like this? Nothing extraordinary sets it off, it just comes, it overwhelms.

What to do?
I don't know.