My Dad Is 92 And Just Finished A Full Prescription

My dad is 92 and just finished a full prescription of TamiFlu yesterday as he has not slept most of the night with agitation and unusual behavior, thinking he was away from home, packing all of his belongings and just really confused most of the day, could this happen after finishing the meds yesterday? He did not have the flu but, due to his age, his doctor said, lets not take any changes as the flu test is only 84% positive???