Up until recently I've used multiple texture packs and mashup packs together. Specifically the Norse Mythology Mashup for the background music and Natural Texture pack and Medieval RP texture pack for any textures, but now some textures don't work right. For example, the pig texture is not at all correct to where it has gaps in his model the sheep is missing a face and is completely messed up, the inventory and most of the UI texture is none of the 3 packs i have active, i uninstalled and reinstalled everything and that didn't work.

Edit: 

In Order to recreate this issue these are the following steps

1 Have the Norse Mythology Mashup pack active

2 Have Medieval and/or Natural Texture pack Active above Norse Mythology

3 Load or Create a world

4 Find or Spawn a Pig/Sheep/ or possibly a Cow

What Happens: you can see their textures are not placed right.

What's suppose to happen: the highest texture pack model and skin overwrites the lower ones