what dosage are you on? I was up to 150. I noticed some cognitive difficulty when i went up to 200. I am now on 100. I also have pernicious anemia...have you been tested for that Signs and Symptoms From a Lack of Vitamin B12 9pernicious anemia symptoms)
Vitamin B12 deficiency may lead to nerve damage. This can cause tingling and numbness in your hands and feet, muscle weakness, and loss of reflexes. You also may feel unsteady, lose your balance, and have trouble walking.

Severe vitamin B12 deficiency can cause neurological problems, such as confusion, dementia, depression, and memory loss.

Other symptoms of vitamin B12 deficiency involve the digestive tract. These symptoms include nausea (feeling sick to your stomach) and vomiting, heartburn, abdominal bloating and gas, constipation or diarrhea, loss of appetite, and weight loss. An enlarged liver is another symptom.

A smooth, beefy red tongue also is a sign of vitamin B12 deficiency and pernicious anemia.

and i was deficient in vitamin d...both are easy to test for. i couldn't tolerate abilify but can tolerate risperdal. i couldn't tolerate seroquel and most antidepressants didn't work and welbutrin hardly works at all.
take care
bobby