Rabbitt illness

Question
Hi I wonder if you can help us we are desperate!
20 months ago I found a netherland dwarf rabbit abandoned in a box on the side of a busy road.  We fell in love with her and kept her, the vet checked her over, filed down her teeth a little and cut off a breeding tag, otherwise in good health.  She has a purpose built hutch, outside exercise area which she was put into virtually daily.  She has an extremely good diet (mix of fresh Kale, apple, carrot) and also shop bought dry mix and fresh water.
About 10 months after we got her, we noticed a large scab under her chin.  We immediately took her to the vet, after a couple more visits to the vet as it wasn't getting better the vet diagnosed mites, treat the mites, gave us "back of the neck" drops for follow on treatment, prescribed antibiotics and advised us to bathe and then thoroughly dry the affected area in salt water, all of the instructions we carried out to the letter.
Ever since, the scabs heal and when she is almost better another attack flares (it seems to be in 3 weekish cycles)  It seems that she is inflicting the damage herself by biting.  I have genuinely lost count of the number of times she has been back to the vet, several vets at the same practice have seen her and the last one admitted that they did not know what was wrong with her.  
Her exercise run is now set up indoors (in the kitchen) to keep her clean.  She is kept very clean, we don't use any sort of chemicals to clean out her living area (just boiling water).  The bite wounds are only to the chest, the rest of the body is healthy.  After the last attack, she has been on antibiotics for the last 2 or 3 weeks, she has just started biting herself again tonight.  I have been looking on the Internet in a desperate attempt to find out what is wrong with her, we can't think what we are doing wrong.  In all other respects she is healthy (lively, healthy eyes / nose / ears) with a good appetite.  She doesn't actually appear to be in any pain.
Have you ever come across this before?  Please help, we are very worried.  Our last rabbit died 3 or 4 years ago, however she lived for over 10 years without incident!
Lynette and Andrew

Answer
Hi,

I would ask the vet if he can give her anything that would deal with the itchiness.  Ask him if metacam might help (it's a pain med) at all with an under-the-skin itch.  It also is an anti-inflammatory so it might help to make the area less sensitive and inflamed.  

I am guessing this may be due to the skin itself healing.  Perhaps there is something topical that can help the skin heal and at the same time help with the itch.  If there is anything that can numb that area.

If the vet believes the problem is with the skin healing, that is one thing.  If it is because of the life cycle of the mites, you need something that can deal with all cycles of the mite.  That may mean more than one medicine to get rid of different stages.  Again, the vet can shed some light into this.  It probably is more the skin than mites.  The skin probably gets tight with the scab, and that is an area she would normally groom, and perhaps she is mistaking the scab to be something matted in the hair that needs to be groomed out.

Either way, metacam may help take the edge off what she's going through at that stage of healing.  If it can work to get her to stop hurting the area again, she'd need to be on it until it's healed.

Lee