it is possible that he has SPD ( sensory processing disorder) which would explain why the medication is not working. More on SPD here – https://www.additudemag.com/adhd-sensory-overload-spd-and-adhd-in-children/?utm_source=eletter&utm_medium=email&utm_campaign=parent_april_2018&utm_content=041418
If the medication is working, then he may have an undiagnosed learning disability (as others have suggested) that is preventing him from learning.
And thank you for mentioning what meds he is now on. It is also possible that he needs to be on a different type of stim medication like adderall or Vyvannse, because Concerta is not doing for him what it should be doing. Do his teachers see a lack of focus or hyperactive activity while he is at school? If so, his meds may not be working for him. More of this in this link – https://www.youtube.com/watch?v=ObnMSU_BagI And also listed with this link are some of Dr. Parkers thoughts on anxiety which you might find helpful.