Hello and welcome!
The sores on the mouth on that other thread were Orf, which doesn't sound like what your goats have. I would agree its more likely to be a mite or lice, or possibly mange.
I would dose them with "Spot On"
http://www.farmrite.co.uk/product/105217/Coopers-Spot-On-Insecticide-with-Deltamethrin-1ltr Shown in this link- I know the blurb doesn't mention goats, but there are lots of products which are not licensed for goats. This is because it costs money to get medicines etc licensed for a species, and on a general scale, there's not enough money or resources behind goats for most companies to do it.
We have used Spot On for years on our goats with no ill effects. You just apply a little bit on top of their head, and another bit at the base of their tail, and it clears up a whole range of mites/lice.
There are a couple of other products listed on this link which may be useful as well.
http://www.hyperdrug.co.uk/Fly-Control/products/132/The other treatment would be to inject them with an ivermectin (sp?) which is actually a wormer, but it works really well on mange too.
Hope that help's- let us know how you get on.
Beth