I am this way in and out all the time I have learned that if you start writing things down on a daily basis it helps that way you can go back and look at how far you have come whether it be frontwards or backwards. It took me a long time to start writing again but once I did it was great it helped me. hope this helps you a little. also mediation is a good way to start to pull yourself back to being you.
I know what you mean, and I totally agree with the other guy. I started writing things down every day. Just write a paragraph, or a poem, your day, your feelings, and email it to yourself every single day and save it in its own folder with the date. Once you get a good collection going you can go back and read some and it'll make you feel better with your current situation because trust me, after going down the only direction you can go is up once you start a change and although it might be slow and not noticeable, everything will add up.
I also recommend just being by yourself for a little bit (days). The fog might be because you've just forgotten what deeply matters to you. Don't go on the internet or your phone, don't text anyone. Just be by yourself because sometimes your environment turns you into a person you're not. Once the days pass, hopefully the fog will have been lifted and you'll come back to the things you love eagerly. If you want to do this, don't just lay in bed all day. Go outside and sit in your backyard, ride your bike in a quiet place, just stare at the sky, eat healthy home made meals that you made yourself. It'll make you feel good about yourself. Good luck