DD11 was diagnosed dyslexic 2 years ago (4th grade) after falling apart in much the way you describe. She read at a post-high school level at the time. She was also struggling with "careless" errors in math to the point that she was risking being retained in math (err, rather, deaccelerated). We've traced that issue to a combination of attention (she scores just this side of not ADD) and a weak auditory memory (related to the dyslexia). A few accommodations, mostly focused on reducing the copying she must do, and some training on cross checking have helped. She remains inconsistent, and errors like you describe still occur -- bad for one test, gone the next -- but her abilities now come through more clearly.
Good luck getting guidance and answers from the testing.
