Hi , I'm James DVM MRCVS and would like to help you with your question
I tried looking up treatment with Flowers of Sulphur and could not find any research or articles published i regards XXXXX XXXXX on dogs.
I would personally not advise to used anything that has not been studied as it cold turn up to be harmful for animals . There are many drugs and herbal medications which are good on people and toxic to animals so I would advise against use.
If Nero's flare up are caused by an environmental factor then there are many simple medications which can help with reducing the itching .
Piriton would be one of them .
This is something you can but over the counter (make sure it's piriton and no other lookalike drug) .
try giving a 4mg tablet and see how it works (you can give it up to every 8 hours at first)
you can also try and see if you can locate the cause of the flare ups (there are special blood tests which help do so - called 'York tests')
There are many means to help Nero and I would be happy to discuss them with you.
if you wish my help further , let me know.
Thank you for your answer will try this for Nero.