meditation

Hello everyone I need some help I am newbee at meditation and I want to tell that when ever I try meditating I am continously disturbed by some what tickling sensation in middle of my forehead or in other words  pulling and pulsing sensation on my forehead. so my concentration breaks this happens every time wheater im trying to astral project or simoly visualize it continiusly disturbes me . I want to know what is that and how to stop it