Not a CPC here, but here are my thoughts...your second code is not to the highest level of specificity as needed, but your third code is, because it specifies the class of drug that is causing the adverse affect of ataxia. But you have a D on it, when it should be an A, if the patient is receiving active treatment for the adverse affect. I would drop the second code entirely, and use the third code, with an A, if it is active treatment.
The ataxia code seems fine.