My observation from what you've written is that this is bringing the fear of rejection to the fore with you and that is what is uncomfortable rather than the crush itself.

Could you try separating the feelings, and just enjoy the crush for what it is (a nice feeling for an intriguing person)? I think we all get crushes sometimes, even if nothing comes of it, it's part of being alive.

You sound like an interesting thoughtful person, even if it turns out he isn't into you in that way (not that I'm saying he isn't) there will be plenty guys who would be.