Are you sure about his weight? He looks very small. Six weeks is too young to be away from the litter. They should stay with mom and litter mates until they are 8 weeks old. He looks thin, and I'm not sure if he is purebred. Sleeping a lot is normal, especially if he is younger than the six weeks they said he was.
What are you feeding him?
Where did you get him from?
BH, OB1, TR1, AD
Rottweiler/Hairy Dog mix?? Shelter rescue
Gryffon Vom Wildhaus