I have been very forgetful the past few days, kind of frustrating....I have had frequent headaches for about 4 days, today it is constant. Having lower neck stiffness, lower back pain. I have also noticed some days I will have cramps that are mild, that come and go throughout the day or night. I am having heartburn after everything I eat, and if I eat like a full meal, a little while later I will start to get sick. Most of the time it comes with no nausea, it just comes. I find that my nose is a little stuffer than usual sometimes throughout the day. What could this be? I have missed one period I believe, unless I got the start date wrong. It would be late by 14 days. I took two pregnancy test on 13 days ago, both negative.