Photos out of date order on iPad Air and iPhone 5

with installing the last 2 upgrades this year, my iPad Air and iPhone 5 have randomly shuffled some of my photos out of date order. This is so annoying and frustrating because I can't put the photos back where they belong. The first time it happened earlier in the year some photos completely disappeared and others appeared twice and out of date order. Two days ago 20 photos from 2013 and 2014 appeared under 2015. Can anyone help?