What Causes Severe Joint Pain?

Hi there, I ve been experiencing severe joint pain (knuckles, knees, shoulders, hips), as well as, pain in my back (upper and lower), as well as abdomen all pain and breast pain, and a migraine for 4 constant days I though it might be pms, however, it s irregular as I normally have a bit of a sore back/right leg, and feel very tired. Also, I ve only had migraines 3 times in my life and they were over in an evening. I ve had on and off nausea, and neck stiffness and pain. There is no way I am pregnant. What could it be?