How do I tell someone how I am feeling?

And Im not talking about telling someone that I like him, he already knows.

Its just that Ive been distancing myself from him, all of sudden, and I no longer know how to tell him how I feel.

Mostly because I dont know how Im feeling.

How do I find a way to;
i) figure out I feel?
ii) tell him how I feel?

Any ideas?