I have suffered with migraines for years (just turned 40) but lately they have been changing. Today I felt a popping sensation at the back of my head near to my left ear. It was accompanied by a strange sensation like dripping within my head. I found it very difficult to concentrate due to the nausea and intense pain and a colleague noticed that I had started sweating. I took 600mg of Aspirin which really helped. Though the back of my head was very painful for a long time afterwards. What do you think is causing the changes in my migraine?