I would like to understand your "problem".

I read your post a couple of times but I don't know what it is really saying. You are not cut out for self-employment (many, many people are not, I dare say. Much easier to have someone managing your time for you than yourself.)???

You don't know how to market yourself? Again, I am not so sure this is a skill that comes to us easily, as most of us don't need to do it. Facebook, Twitter, LinkedIn, those are mostly social networking sites (well, Linkedin, I am not familiar with, is that the business networking site?). So, is it that you need help marketing yourself and building up your book of business?

Freezing up on the job, not multi-tasking. Hmmm... most people I know that say they can't multi-task usually seem to have a objection to it. I see it as they won't multi-task, not that they can't. So, maybe that is something you can overcome? I can't imagine not multi-tasking. But, that is just me. Maybe you are really just more singlemindly focused, and that isn't an issue as long as you can stop and start, pick up where you left off, etc. Otherwise, I can see it slowing you down. But, that is a skill set you can learn.

Writing a list of daily to-dos is a great idea. I think it is Steven Covey that broke things down in the 4 quadrants, and maybe you can look into some of his liturature. I worked with a guy that was wedded to his list to the point of missing out on some major events just cause it wasn't on his list. Maybe the opposite end of the spectrum, I dunno.

As for applying for disability, are you disabled? If so, apply for it. Nothing wrong with that.