clio - if you think about re-homing another dog, it should be because you want it, and it will fit in with your life style. Another dog shouldn't be got as a companion to fill a void.You have so sensibly said this is not an option so why not think of taking your chappie to dog training, gentle agility, whatever, -- sounds as though he enjoyed the one-to-one interaction with the sitter plus the attention of the pup and feels not sufficiently stimulated at home now. It's always an upsetting time for woofie when Mum & Dad go away (thank goodness you had a great sitter!) and it will take him a while to re-adjust - I house sit several properties with different breeds and they all react differently. One needs to be surgically removed from my left thigh when I leave, he appears to love me to pieces but I suspect its only him reacting to the situation whereas another lives in my pocket 24/7 but when Mum & Dad come back, I don't exisit. My advice is to just continue with your routine because he has to adjust to that but maybe try and find something extra to stimulate him on a regular basis - he obviously enjoyed the challenge. -keep us posted.