Skin uploads as Classic instead of Slim

I made a skin (That I made sure is slim) and attempted uploading it to minecraft in every possible way; Minecraft.net and the launcher. They'd upload the skin, but only as a classic when it was a slim. This would cause it to have black pixels. Whats weird is my skin was just fine before; slim and perfectly fine. I never even changed it it just happened out of nowhere when I launched Minecraft today. It's very frustrating and I would like some help.