Hi, robyns right on the mark there. It sounds like common ear mites, one of the most common rabbit problems. Like robyn mentioned, oil works, I havent had much luck with the new water soluable baby oil, it dos'nt seem to work for me. I've had better luck with mineral oil, use enough to cover well every day for abouty a week not an excessive amount of mineral oil but be sure to cover the inside of both ears very well, and be sure to treat both ears even if you dont see anything in the other ear just go lighter on the one. If you dont have access to mineral oil you can surley use baby oil like Robyn said, however I would use cooking oil, or olive oil, or even the regular baby oil, befor the water soluable type. The best method is the last one mentioned, the ivormecton pour on type, This product is spelled several ways, all close spelling and all the same product
Like robyn said 3 drops for a normal size rabbit for a miniture I would use only 2, and if its not 100% cleared up after 5 days repete the dose again.
Watch the other rabbits because it is likely they will come down with them within the next 8 weeks, they may be started already and not yet dectable by the eye alone, you could go ahead and treat them now too or just keep a sharp eye on them. It usually goes around, and comes back from time to time, easy to cure but nearly impossible to stop completely.