Hi border,
Really, the best way to clear brain fog is to get better! Not sure what you are taking right now, but continued treatment should address this.
I think it's a good sign that you want to get some things done. Keep searching for things that you CAN do at this point in your ability level. Don't keep beating yourself up or hankering for what you can't do. There is no peace to be had in that!
I tell there have been times I have been so frustrated and then I see someone with a perfectly good brain not using it and I get even more frustrated. "Hey, if you're not using that brain can I use it?!!!"