Whenever I use the skin modifier with a mirror modifier the mirror modifier creates weird problems on the back portion of the mesh...Help?
Hello sneekycockatiel234, first of all the Skin modifier can behave crazy at times. Mark Root and Mark Loose can have huge impact. Now I tried to reproduce your situation, but couldn't get the same result. I notice though, that the Mirror Modifier works along the Y-axis, although it says that it uses the X-axis to mirror. So your rotation is messed up. My guess is that when you added your Plane, you rotated it in Object mode or just clicked Align to view, which also changes the rotation! Then when you collapsed them in edit mode to one vertex (or deleted 3 of the 4 vertices), you ended up with 1 point that was rotated! This sounds crazy, but one vertex in Blender also has orientation (see screenshot).
So, try again, add a Plane, immediately go into Edit mode, Alt M , merge at centre and go on from there.
Btw, you also seem to have double vertices. Your middle vertex doesn't seem to be connected to it's neighbours. If you run into problems like this, Remove double vertices might help. In other situations, when you get weird shading, shift N to make normals consistent should be one of the first things to try. I hope this is helpful.