My advice would be teach him to ignore other dogs and quit the day care. If he's fine in the house he doesn't need it. I would also question exactly what he is doing in day care?? Most likely where your problem started and where other dogs dealing with him problems are coming from?
Most likely a Dominant Dog? If so he's most likely learning to push around other dogs once a week then on walks you don't want him doing that.
Not saying any of this is the case but that is my spin on it.
My advice would be to ditch the day care and teach him to ignore other dogs. If he is a dominant dog and gets a free run once a week to push dogs around ...well that's what he's learning.
Confused messages who's he learning from you or day care?