Dear Member, I can understand your worry to support your child. As an expert, we can point you to many possibilities - anxiety, stress, performance difficulties, procastination, perfectionism, etc. Only complete assessment can give better planned intervention. Either work with an expert if possible. On your own, you may sit and speak to your child openly. Assess why is he getting worked up about work and what is building up to disable his concentration. A friendly heart to heart may also be a good start.
Next Steps
Work with an expert to learn stress management; time management skills and study skills. Teach the child to prioritise and achieve task by task.