Well, I'm new here but not new to raising rabbits. Have had them off and on for 30 years. I use VetRX Rabbit Remedy, you can get it from most US feed stors or order a bottle form Amazon that I know of. Be sure to get the one for Rabbits as there are other formulas of VetRX available.
It is a natural, herbal treatment for snuffles, ear mite, ear canker and pneumonia. I don't trust it to be enough for pneumonia but, it does work well for anything else it claims to treat.
For mites, just warm it and put 2-3 drops in the affected ears(s) once a day for 3-4 days, swab it around with a cotton swab if the upper part of the ear is sore.
It doesn't affect harvesting the animal for meat so, no wait on that if that's what you do, also safe to breed and treat nursing does with it (I have done it many time with no problems).
As a side benefit, it's perfect if you need to foster kits, just put a drop on both the biological kits and the ones you are going to foster then, put them all in the nest. The doe smells the camphor in the VetRX and will take the new kits w/o a problem.