Quick update.....
Boris got gradually better over the course of the weekend but we took him down this afternoon just to get the vet to check him over anyway. I was worried.
It
was a reaction to the flea treatment, the medication is called ProMeris and the vet says it has caused this kind of reaction in many dogs - vomiting, diorientation and losing locomotion in their back ends. She's said that if this ever happens in future to wash the area where the lotion has been applied repeatedly to try and minimise the effects. (Don't know why I didn't think of that at the time
)
Thanks for everyone's advice & kind words
and be wary if you get given ProMeris - nasty stuff
Karen