"the bottle is the only difference in diet "
Actually, the bottle and the hay are the only things the same, unless your feeding them the SAME grains, sweetfeed, etc, etc, that they were eating at the other place, if not, then their diet has changed.. and goat don't do change well... my advice?
Keep doing what your doing.. don't switch anything out for anything else now.. it will take them a bit to adjust but if you switch back now, you'll just be making
another change, and stress from the move, new feed, yea that will do it....
The whole cow milk from the grocers is just fine, only it's pasturized and so no good bacteria.. I would recomend against replacer as I've heard a lot of negative things about it.. and again, that would be another change..
I would give them some Probios for 5 days (5g) and some baking soda.. the baby, you can put the bs in her bottle (a pinch) and the older one, I just wet my finger, get some on the end and wipe it on their tongue.. this will help with the upset tummy and the Probios will help maintain their rumen..
I've had my goats on horse feed for a long time but I used a "dry mix" which has less molassas (which can cause tummy aches)..
my goats won't eat horse pellets .. If it helps, find a feed that is readily available to you and if it's not what your using slooooowlly switch them over. I have mine now on Purina Goat Chow and they love it and they look great.
Also, personally, I don't use Pepto, or Kayopectate or that stuff as I'd rather take care of the problem than cover up the results.. It may take a few days, but consistancy here is the key and you should see things get back to normal soon..
Good luck with your new acquisitions.. it's a learning experiance, but a fun and rewarding one!!