Game constantly freezing up, music constantly skipping on title screen, unplayable multiplayer.

Where do I begin? This started a few days before the 1.11.0 update and is still happening. My Minecraft is extremely buggy to the point where even singleplayer will act up. Every time I start up my game I see a black screen for a while before the white Mojang loading screen decides to finally pop up. It gradually starts taking longer everytime I start it up. I'm then greeted with music constantly looping the same one note as the game loads. It will freeze and mess up the music like that whenever the game loads anything, such as the store or selecting a world. These freezes can be really annoying since they last around 10 seconds, and happen whether I'm in single player or multi player. I am unable to play online at all in servers or with other friends because it will disconnect me after a few minutes, or even a few seconds after I join. My friends have the issue as well, and it is not my internet that's the problem. It is only a Minecraft issue. On top of that my skin is always changed back to either one of the default ones for unknown reasons every time I open Minecraft and tells me my skin can't be used in cross platform even though it says it can when I go to reselect it. Please fix these bugs, I used to be able to play Minecraft just fine until this all started happening.