I had a Thunderclap headache 2 years ago and I was in the hospital for 8 days before they could stop it. It started like my normal migraine headaches. I felt a headache coming on at night and by the morning I was in immense pain. The next 3 days I was in the worst pain of my life. I don't remember much except nothing was easing my pain. I finally went to the ER and was admitted immediately because something in my blood work indicated a possible brain aneurysm. Nothing was stopping the pain until they finally did 2 days of IV DHE. The biopsy thankfully showed no blood clots and I was able to go home after 11 grueling days. It did somehow change my migraines, I would not have any symptoms that I had a headache coming on. They just hit hard and quick. I now have headaches every day, but they vary in pain. My Neurologist has not been able to find anything to help them or decrease them. So now they think I have NDHP. My Dr has moved and I currently don't have a replacement. Not a lot of good Migraine Drs here in SC. I did nothing special that caused it but I hope and pray I never have another one!