From what I can find, sulphur ointment is often used against scabies in cattle and humans. But there are always some individuals tgat are especially sensitive to certain substances.
I read up a little bit on mange. According to several sources, the intense itching can persist for 2-3 weeks after the mites have died. The rabbit can self-multilate due to the itching (for example gnaw at its paws) so sores arise. Bacteria can then infect the sores. The bun constantly gnawing/itching also prevents sores from healing. Bunny-safe antihistamines can be used to relieve itching.
You should do repeat treatment with either the Dectomax or with Ivermectin. A study from Turkey suggests that ivermectin works faster, but it also says that after 28 days, all rabbits were free of mange regardless of whether they’d been treated with doramectin or ivermectin.
https://www.ncbi.nlm.nih.gov/pubmed/20391367
You also need to clean the rabbit’s living area and Medirabbit suggests treating it with an agaricide like Virbac. The rabbit mustn’t be in the room when you apply the Virbac, because it’s toxic to buns. Fipronil, another antiparasitic, is deadly toxic to buns and must never be used.
http://www.medirabbit.com/EN/Skin_diseases/Parasitic/Mange/Sarcoptes.htm