Please help ,, its been more than a month ,, am experiancing an annoying dry cough ,, specially b4 i sleep?

it comes and goes in intervals,, sometimes during the day but not as horrible at night b4 i sleep i even sometimes wake up due to my cough ,, its dry not painfull but too anooying it feels scratchy inside ,, the thing is i am not sick ,, i dont experiance any flu or fever .. i went to the doctor all she did is giving me a coughing syrop ,, but it doesnt help at all .. it only fades away when i drink something walk like tea ... its bothering me much now adays ... i just woek up due to it .. and posting this online for some help ... thank you