What Causes My Serious Headaches Which Radiates To The Left Eye?

Andrew Etokimo, 49, on school summer holiday now. I do summer job in the college. No stress. I sensed serious headache in my forehead and radiates to my left eye. My blodd pressure went up to 140/100. Went to Doctor and was told to stay hydrated. I do this but I still have the same feeling. I wandoer what could trigger this.