In my experience, my headaches never went away no matter what position I was in.

The only way you're going to know if you have Chiari is to get an MRI.

My PCP sent me for a "just in case" MRI when nothing we were doing was helping my migraines and other issues. She was doubtful that anything would show up and wouldn't you know I have Chiari.

Fortunately for me I have access to an amazing NS and residents. I was in and under the knife within 3 weeks of finding out my diagnosis.

Granted I'm having issues now, but I think it was my fault. I started doing too much too soon, but the surgery did help a LOT. My headaches, while back, are not nearly as bad as they were.

If you are having issues with your head I'd go see a neurologist. Get an MRI or CT Scan and go from there.

Good luck.