Hi. I can understand what you must be going through. Experiencing headache when faced with stress is very common. Even your symptoms of inattention and decreased concentration is related to the same.
You should seek a psychiatric consultation to undergo complete evaluation for other symptoms of depression. With treatment in form of medications or psychotherapy, you will start feeling better.
Next Steps
Seek a psychiatric consultation.
Health Tips
Start exercising daily. Talk to someone close about your problems. You will feel better on venting out your emotions.