Glitches and unstable

Since the last update minecraft has been extreamly unstable and glitchy, when going trough a portal either to or from nether you never know where you will end up, i kept going in a sircle 5 times, always ended up at where I started even tho i went in to another portal then the one i came from, once i ended up inside a wall only to die and loose all my stuff, another time when i was going to take the Dragon i spawned in to nothingness and ofcourse died and lost all my stuff.... again... last time i died i got so frustrated that i rage quit the game, i was meining inside a mountain and the game started shaking and glitching and all sound went away, i stopped and was thinking.. this is wierd... then all the blocks came back and suprice suprice, i died.... again! I got a normal unchanted pickaxe and started morning to ser if my stuff where there  inside the wall but they where all gone, now i have to work my ass of to get all Diamond gear with enchantment back for the third time... pleas do something!!