Hello,
Based on your symptoms of a headache which starts with bending down especially while studying, and is associated with nausea, one can think of probably a sinus headache, but it also requires to note for any other symptoms of the timing of the symptoms in a day, exact site of the headache, any history of frequent sore throat/ ear block/ ear discharge/ nose block/ discharge from nose and any other complaints.
With also mentioned symptoms aggrevated with movement of head and exercise, any complaints of giddiness, difficulty in movements in neck, any pain along the arms or hands is alo important to note.
A detailed noting of your complaints is currenlty required.
Next Steps
With such a chronic complaint, I would adivse you to consult a physician, to approach your concern in a detailed manner, to move forward with required tests, and get the most appropriate treatment for it.