Skin switching Models on its own

In all versions, today I logged on and my skin was magically changed to the steve model with the large arms. This is weird because I only use the slim alex model, and when I tried to change it back, It stays the steve model with the black lines on the back. I tried to change my skin through the launcher and the minecraft website and to no avail. I have made sure to click the slim option too so I know it is not a problem on my part. Please fix this