are you giving him things to chew - my puppy loves her nylabones and will give them a really good chew for 20 - 30 mins at a time some times. Could it also be an attention seeking and he is bored - do you do short training sessions with him every day say a couple of times a day for 5 to 10 mins (getting him to do sit, down, leave, stay etc?).
Does he bite you when you enter the room or is it when you are already in the room. Is it ankles he is biting when you are moving round or is it when you sit on the floor and he tries to bite your hands / arms? I would have thought you could say ouch (i would grade the loudness of this with how hard he has bitten you and also leave the room for a few minutes or sit on the sofa and ignore him)