The file preview on google drive is broken so can't see a list of mods (which mightn't help as I'm not much of a mod maven).
From looking at the IMGUR pic it looks like the skin.png is not the expected resolution... at a guess whatever mod is doing this is expecting a higher resolution skin than it is finding…
Try doubling the size [dimensions] of the png file for the skin (it won't look good, but will at least let you know if that is, indeed, the issue).