puppy + arguments = broken family

[cakeboss]

hello,

I'm 19 and have a 15 week old puppy, he is a springer spaniel crossed with a staffy and lab! he is an amazing dog with me my sister (23) and my mum and dad, as well as anyone he sees and any other animals.

He has always been good but since I have finished college he has been naughty , I am at home with him all day and all evening and go out occasionally or go to work but apart from that I will be at home with the pup. When it is just me and him he is good as gold, he will sit on my lap, play with me, go on walks and has immaculate behavior as soon as a member of family come back from work or someone else comes and sees the pup he bites me, not anyone else just me! it is really upsetting and starting to cause some really serious arguments and issues at home. I have tried every technique for him to stop and have been left with some nasty bruises and cuts! but then as soon as they leave the room he is perfect again.

can anyone please explain why this is happening and how i can make it stop! please I cannot cope with this any more.

Thankyou so much x