Conversation. Only words can help. Who do you want to express yourself to? If your T, just tell him/her what you've told us or tell about what the thoughts feel like sitting in the back of your head; their size, shape, color, weight, flickers of images, things they remind you of, anything at all. Everything in our head has to be put in the shape of "words" to be communicated/expressed. That's all we have with each other. Yes we can do art, dance, etc. but that's only for us; other people can't read our minds and what we're expressing, what they see is different than what we see.

If I were stuck, I'd work on remembering my dreams and working with them, associating them with made-up images until a real one stood up and identified itself.