First take a few days off. It's been a long year, lots of marking, time for a brief rest- so say til next Monday. No point pretending to work.
Then next week, make your first job to plan out your next 6-9 months. I don't do this in a sophisticated way, but list every single thing that you think you will be doing and bullet what you need to do to achieve it (e.g. write paper on X, to submit to Y, I need to: get the data off Darren, write email to co-author, spend 2 days on SPSS, write intro, write methods etc). Then set a realistic date for that end point.
Prioritize which you are going to do first- and then only do that one for a week to kick it off.
Then spend just one hour (you can always do more, but one solid hour writing is better than 5 faffing about) totally focused. Set a timer for 25 min, no web pages open, just focus on doing that one paper/grant. If you are very tired, just fix the references. The do another 25 min. It could even be just rereading it from the day before. Sooner or later, you'll hit writing- so write a paragraph in that hour, then one the next day. After a month, with a few days off, you'll have done 25 hours on that paper.
Every day, plan what concrete action you are going to do the next day (in a notepad/journal or online) and do that specific thing in the hour. That way you don't spend an hour trying to remember what you are doing!
Keep going.
This is the counsel of perfection, I don't always do it, but the hour method really works, and moves you past panicking/procrastinating/not knowing what to do next.
You don't have to do it this way, but any type of planning, then writing with concrete goals for short concentrated bursts works. Still painful though!