Baycox - the one for used for lambs etc. Vet prescription under cascade. Not cheap, but lasts for ages. You will need to be able to weigh them reasonably accurate, and the easiest is to put it into their milk, but if they are weaned then drench is the only option.
Cocci has a three week incubation time, so you need to watch them again in three weeks time.
But don't keep drenching them unless absolutely necessary, there is already resistance to Vecoxan and they will build up a tolerance to them - adult goats should not get ill with cocci.