Help? Random Dark Splotch on my CC?

Third time meshing (I think I got the weight transfer down this time...hopefully :/)
But I'm trying to make a dress this time! For my bases, I used the nude top and nude bottom and for my reference mesh, I used the chemise! I followed a method that involved doing a weight paint and a vertex paint

So the thing is, the preview and my game both show a funny dark splotch on the clothing garment:

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So I kinda found that if I play around with my texture, I can make it seem like there's no black patch by painting the part of the clothing that should be there white...however, the thumbnail still shows and it's easier if I can make more textures without coloring each part white :/

Also, when I zoom out and watch my Sim walk around, it's like a part of her dress is attached to her foot. Is it a problem with the LODs?
Here are my blender files for reference:

Download Here!

Thank you in advance! I'd really like to know what is causing this problem so I can troubleshoot more efficiently next time