I feel like I am getting dumber

I keep misspelling things and mispronouncing things and misreading things and forgetting things I feel like I used to have no trouble with. I'm diagnosed with ADD so that is probably why but I feel like I am getting worse as of late. I am struggling to read things and comprehend what I am reading. I am eating plenty, drinking water, and getting sleep but still my brain isn't working right. I used to be good at this. There is just something wrong and I cant figure it out.