What Causes Severe Headaches During The Day?

I am Georgiette, a young Ghanaian lady of 24 years and i need an advise. I have been experiencing severe headaches with no body temperature rise lasting for 2 and sometimes more for the past 3 years. I experience this headache late morning through the afternoon, evening to late evening, the headache stops by midnight and start again late morning. I believe i have this headache because a metallic canopy fell on me during a storm and after 2 years i started experiencing this. Its normally severe when i busily walk for 2 - 3 hours either morning, afternoon or evening. Also when i walk in the sun or begin to think so much.I have visited several hospitals but all they give was paracetamol which is unable to solve it even not for the moment taken. Could any doctor explain to me what this is because am getting worried day after day.It makes me feel there is something really happening in my brain right now and i need to work it out. Thank you.