FREEZE!!!!

zombies,slime,Enderman,silverfish and wither skeletons hit me from about 20 blocks and they are not anywhere around me when Im in a nether fortress and in F5 mode i get hurt by wither skeleton and they freeze in the over world then a second later i get hurt same with players on my realm and servers once i go on the floor i just get hurt and it says i got killed by ex[player=name] when i go on the void it says disconnected from server.