Hmm, is it possible that something is going on in your life that is causing stress at the moment? I found around about 1/2 way through last year things got a little harder for me and it was my writing (both here in the creative zone and for my uni work) which suffered. Of course it could be that you only need a break for a day or two. I find it helps to write down in point/note form what will happen, don't worry at all about the details, just think of them and try to remember them. Then pick the part of the post that stands out to you and start there. Piecing each of the parts back together at the end so they flow can be a chore but it can help to break through the initial barrier. Don't forget to get rid of distractions, no 'oh I'll just check Reddit for a minute' or 'do I have any new emails? I should check' or you'll loose the flow and hit the wall again when you come back. I know this blasted feeling all to well at the moment.