Avoid taking Aspirin or Ibuprofen because they prevent healing-
When NSAIDs make pain worse - A significant public health concern | Caring Medical
If his head hurts, he should stop what he's doing and rest.
What Physical and Cognitive Rest Really Mean After a Concussion | BrainLine.org
Pain is the body's way of alerting you that what you're doing is causing damage. The opposite is also true - if you stop said activity then the pain goes away. So that pain should not be ignored.
Consider taking it easy for the summer so his brain has a chance to recover.