I agree with Dr. Anusha. Your headache is most probably due to personal and work pressure. You need relaxation and you can try meditation, change working environment if possible.

I don't know whether u have got an MRI Brain done, because persistent headache for two and a half years is a clear cut indication for MRI Brain. A proper clinical history of your headache and neurological examination will guide you to a diagnosis.

If you have persistent headache, you have to meet a neurologist, since you have ruled out ENT causes. High stress in daily life related to personal/professional problems may be contribute to intractable headache not responsive to medicines. If that is the scenario, consider alternative stratergies like yoga, meditation and positive biofeedback. Maybe even a short vacation. Long hours on the computer may cause eye strain and headache..Try to limit your screentime and take short breaks...