Flatter than flat since I was a little kid as it runs in our family. Tried orthotics somewhere about 11-12, but it just seemed to hurt more. Maybe it was because it was probably cheap plastic and technology from 30 years ago. Outside of seeing a foot doc, the best thing I've found is finding the right shoes. I wore Nike forever as a kid/teenager, because that's what you do. Hit college and wore cheap. Somewhere about 8-10 years ago i switched to New Balance. It seemed to be a little better.
One day I actually went into a NB store because Academy didn't have the style or color I was looking for. I asked the sales dude for a model ABC in XYZ color and size 10. He asked a bunch of questions about use, fit, activities, etc. I thought he was just blowing smoke and trying to upsell. He measured my foot, and asked if he could suggest something a little different. He brought out what I thought was the most God-awful short bus looking thing ever created. Only came in one style/color, and had this You-get-to-park-in-the-handicapped-spaces part at the instep. My first thought was aw hell naw!!! I reluctantly put this thing on and was amazed at the difference. He also recommend some inserts to go in the shoe. Yeah, here it comes, I thought. But damned if they didn't make a difference as well. I hopped around, walked a bit, etc. I even tried the new combo on one foot with my shoe on the other. Difference was night and day. I've worn the same shoe, or the newer version, ever since. I've even gotten the inserts to stick in my boots, and NB has a sister/nephew company called Durham that makes casual/sort of dress shoes. Worn those with success as well.
All that to say, have you tried different shoes? I don't have the ankle issues I used to after switching.
