would it be possible for you to put his crate in your room with you at night as he has come from a rescue place it may be that he is just scared that your going to leave him , they must see so many people come and go it may reasure him that he is there to stay and your not leaving him . its a fine line between ignoring what you dont want and being patient with the poor boy . im sure given a bit of time he will be ok labs and collies are good dogs and not a bad mix to have although the collie part of him may make him a little more highly strung .post some pics if you have any .
Andrea