My Minecraft Skin is different Versions

When i changed my skin it said i needed to wait a bit for it to change on 1.7.5.
But when i logged on after waiting my skin was the same from before i changed it. So i went on 1.7.9 and the new skin was on that version and when i went BACK to 1.7.5 it was the same skin from before. I went on nova skin to look up my skin i had on for everyone else and it was a different skin from a while ago. So i dont know how to fix it becuase on 1.7.9 when i join a server I'm a steve so i REALLY need some help!