What are blackouts, loss of vision, and impaired balance common symptoms of?

A few possibilities. Dehydration, low blood pressure, uncontrolled diabetes, and high fever are among the many causes. There are certainly other conditions, and anyone who is experiencing these symptoms should be seen by a physician promptly.
Check toxicity profi. Have your blood tested for toxicity profile from metametrix they do these testing and your insurance covers this. You need to have this ordered through a doctor.