Headaches and neck pain

Hi,
I'm 33 y/o female, mother of 4, and have had a headache and neck pain for a couple of weeks now. It comes and goes. I feel fine sometimes and then it will come and bug me for a while and maybe feel better again later. No certain time of day that this happens. I don't know what is causing this. My doctor thought it could be due to my seasonal allergies, but not sure if that what is causing it. The neck discomfort kind of feels like when you are straining your neck like you do lefting something heavy. But like I said it comes and goes not constant. My upper back was hurting me too, but that is not bugging me now just the head and neck pain. Do you know what could be causing this?