/ic/ - Artwork/Critique

Can anyone tell me why that foot looks so fucked up? Any advice and tips in general with how to improve this would be noted. I'm also wondering what I need to do to get the pixelated lines to stop breaking the way they are. Do I need to expand the pen lines to properly vector this? I'm trying to create something that won't matter how I have to scale it later- basically a vector. C&C welcome, I'm here to learn.