Sorry for the delay in getting back, I was out all day as my goats have started to kid today.
I wouldn't worry too much unless it goes to proper diarrhoea, but cut back a bit on the protein rich stuff. I don't weigh my goats' food anymore, but measure scoops. I fond that coming closer to kidding they get "selective", so I offer soaked warm sugarbeet, oats, calf mix and diary nuts in separate little mounds in the four corners of their feed bowl (normall it does get mixed) and it is quite varied on what gets eaten and what not (and it changes by the day)...
My BT's are more likely to just eat all they can, the GG's often slow down more towards the end of pregnancy.
You may want to check on worms maybe, if they do go out and it has been wet and not so cold?