Started drinking water to be healthier but i find just drinking water gives me a headache why is this?

"Brain Freeze"?: Brain freeze from ingesting ice cold water & foods is common & multifactorial, as are headaches. Such pain can originate from the skin, fat, muscle, blood vessels or within the cranium from great venous sinuses, their tributaries, the dura & its arteries, the falx cerebri, & large arteries at base of the brain (all of which have pain fibers). Could try room temperature water & assess response.