I have almost the exact same problem as you describe with your nails. My thumbs, index fingers, and middle fingers (both hands, like a mirror image) only have continuous patterns of white spots flowing out. I haven't found any relation to anything.
One friend in Japan said it was a sign of good fortune, I hope it's true but it could also mean disease.
But I'm a 26 year old healthy Canadian guy, exercise regularly, eat very healthy, I'm really lost. Maybe it's the air in Japan, and the pollution from China coming out in my nails. I dunno if anyone can email me back id be happy for the help!