George is just coming up for 6 months old (25 weeks) and believe me I know this seems a huge amount of time away right now! but I just want to let you know there is some light at the end of the tunnel!
George was MENTAL! he would do laps of the living room, wall of death on the sofas I had so many bites and scratches on my arms and legs from his 'mental puppy moments' as we called them - one day both we were both stood on chairs refusing to get down until he calmed down becasue we had gotten bitten so much! and those puppy teeth are sooo sharp! he's drawn blood only once soo far?! you lucky thing!
(as you can see from the name feet were a particular problem for a while there!)
yelping just made him more excited, ignoring him and turning your back on him just meant you got your ankles and bum bitten a lot! we didn't know what to do at all!
I know this doesn't sound encouraging so far

but don't worry this story has a happy ending
In the past month or so he has calmed down sooo much!
It does just seem to be a phase (thank god! I thought we were doing something sooo wrong and were going to have a viscous grown up dog that would attack someone and have to be put down!

or "oh Christ! I don't think I can handle this for the next 15 years!")
things that did help us though....
when we came home, or even just had left the room for a minute - whenever we came back into contact with him we ignored him for a couple of mins - he would go mental for attention, start him biting for attention - BUT!! after a couple of minutes he would go off in a sulk and once he'd left us alone we called him to us and stroked his head and neck - he would just melt into submissive on the floor! I think it was showing him who was boss from the beginning and would set us up on a good note for the rest of the evening...
and when he's already mental (I know people are going to shout at me for this one - but if you'd been there you would have done the same thing!) - if he bit too hard we grabbed him by the scruff and plonked him in his crate for a 10 minute ignore him and time out! (& recovery time for us!)
nothing worked like magic but these couple of things really helped us!
sorry! super long post but I really wanted to give some encouragment because for a while there we were really not enjoying having a puppy at all! and we had expected mental! but its soooo much better now... he's at least manageable mental
Good luck! & Keep the faith!
laura x