I have a pounding headache that affects the left side of my face (head, eye and neck) and it can be extremely painly most times. what is the possible?

Few possibilities: Migraine headaches are commonly described as pounding, and commonly occur on only one side. Headache with pain in the face, eye, and neck could be due to a migraine or could also be related to sinusitis (a sinus infection). Headache can be a sign of a serious problem. If you have never had a headache like this in the past, you should be evaluated. See: http://undermigraine.blogspot.com