So, there are two possibilities that I think it could be, sarcoptes mange or treponematosis(rabbit syphilis).
The white crusts on the ears look like it could possibly be sarcoptes mange(burrowing mite). Even with a negative skin scrape this is still a possibility. It's normally treated with either ivermectin or Revolution(selamectin). With the ivermectin, vets will usually give it by injection at least 3 treatments 14 days apart. It is available otc and can be given orally, however dosing has to be very precise and improper calculation could result in OD and death. Revolution would be the easiest as it's usually a one time topical application, but it is rx.
MediRabbit (sarcoptes mange in rabbits)
MediRabbit (Revolution/selamectin dosing info, 18mg/kg)
The other possibility since it started around the nose and spread to the mouth and eye, is treponematosis(rabbit syphilis). It can also produce a white crusty looking exudate and lesions, similar to what occurs with sarcoptes mange. It's also something that even some rabbit savvy vets aren't very knowledgeable about and may miss properly diagnosing. It doesn't usually affect the ears, but a severe case left untreated could spread to other areas. I see the bottle of baytril in the photo. If your rabbit has been on this, it could explain the skin lesions partially clearing up. Baytril can temporarily help with the skin lesions healing, but it won't cure the disease and it will reemerge once the antibiotic is stopped. Pen g injections(injection only, never orally) are needed to cure rabbit syphilis.
MediRabbit (rabbit syphilis)
MediRabbit (atypical form of rabbit syphilis)
Take a look at the photos and clinical description of mange and syphilis in the links I posted above, and see which seems to match the symptoms your rabbit has presented with and which disease best matches the crusts and lesions you have seen. Then if one of your vets is better about working with you and listening to suggestions, I would suggest ringing them and talking to them about what you suspect it is and ask if you can get the medication needed for treatment. If you suspect syphilis, you can get pen g otc, but only the short acting one(procaine), and you would need to know how to give daily injections of it. It's better and easier to use the long acting pen g procaine/benzathine for treating it(which you would need to get a prescription from your vet for), plus your vet could show you how to do the injections yourself if you felt comfortable doing that.
I'm leaning towards it being syphilis based on your description of symptoms and the fact it cleared up somewhat with baytril treatment(?), though I'm leaving mange as an option based on the photo with the white crusty exudate on the ear, as that looks very similar to mange.
If you do end up treating for syphilis with pen g, it's essential that any leakage on fur is cleaned off thoroughly so your rabbit doesn't ingest it while grooming. Ingestion of pen g can result in fatal enterotoxemia occurring. I would also suggest adding benebac plus probiotics to the diet, no high carb/sugar foods, and a lot of good quality grass hay. This is to help with gut function and try to prevent digestive issues occurring due to the antibiotic. Also keep a very close eye on poop changes. If you see fecal poop that is watery or pudding like(not just mushy cecotropes which isn't diarrhea and an emergency), that is diarrhea and an emergency. It means your rabbit has developed enterotoxemia and needs treatment with questran and metronidazole.
