Hi Martin + Family!
Well, even 'Huge Harry' does the shakes occasionally...and I can never really put it down to one specific thing.
It could be that little Holly needs more food - but then knowing you, and the way you treat/feed your bubs, I doubt that. Have you tried her with Nutrical? Or even a blob of (local to you) honey?
My immediate thought, when you posed the question, was that 4 miles just might be too much for her - yet
Maybe it's worth building her up to that more gradually?
I think this is a really good reason (excuse
) for Irina to go and buy a stunning pup-carrier
xx