minecraft constantly reloading

when i try to play the game, the game constantly reloads, this happens between every 20 seconds to 1 minute. the screen freezes, before going to a plain red colour, it then seemingly returns to the games loading screen, however, rather than returning to the home screen, i am still in the game, however, i have often moved several blocks in any direction, which has led to me loosing my items and also an almost unplayable game