Good day i have had a headache for yesterday morning even today, took painkillers its not going down what could be the cause?

Many causes possible: Most or all people have a headache at some time, such as from colds and flus, lack of sleep, too much driving, long hours on the computer, stress at work, etc... Several over-the-counter options include Tylenol (acetaminophen), Motrin, Advil, Aleve, and their generic brands. A bad or increasing headache, recurrent or weird headache, or one with other worrisome symptoms should be examined.