I am presuming the question is if his problems are related to medication or his illness and if they can be helped.
There is a good chance that his concentration problems and headaches
could be because of medication....more assessment needs to be done for a firm conclusion.
The best way forward is for him to go back to the treating psychiatrist
for he is best placed to help him.
I would also respectfully suggest that actually all of these MUST have been already being periodically monitored and if these have not been picked up, then either there is lack of trust on your part in not disclosing these to your psychiatrist or lack of sufficient monitoring by the psychiatrist ....both of which are not good for your son's health.
Please make sure that he is adequately monitored every 2-3 months, on account of the amount of medication he is on.
Good luck to both you and your son.