What Causes Headache And Pain In Lower Neck?

Hi I am a female age 40. I had a series of headaches three day ago all in the late afternoon that made me sick to my stomach. Now the headache is gone but I feel exhausted at times and have had intermittent pulsating moderate pain in my lower left neck area. I don't feel completly sick I just don't feel well. I am a smoker but not on any medicines.