I would agree with Mr. Keon that, in order to be licensed, the drugs have to be proven to be equivalent. Why a patient's experience might differ, I cannot comment on an individual case.
For drugs to be licensed, we do randomized control trials in which hundreds of patients are randomly assigned to a treatment so we can know the changes that they experience are, in the end, due to the drug. If you only have one individual, you don't know what the trajectory of their illness would have been. Changes in their symptoms and experience may have occurred independent of the change of a drug. We rely on the research evidence that suggests these generic medications are equivalent. I'm certainly not aware of people having an inferior experience that can be directly attributed to the use of generic drugs.