With your headaches, try drinking more water or probably consult a physician - headaches are very unspecific i.e. there can be many reasons, from bad posture to even teeth problems. I hope you'll get well soon!
Meditation can help improve your concentration for longer periods of time if you practice it regularly and have enough patience to keep up your regular meditations. For instance, if you watch our videos, e.g. choose one from our YouTube channel, you can choose important statements as meditation topics to deepen your understanding of the chosen topic(s).
When you have developed long enough concentration spans of about 20-30 minutes, you can for instance use our Meditation of the Inner Temple in order to practice your visualisation skills and also create a basis for active meditations in your inner sanctum later on.