See following threads. I have battled something that sure looks like what you and your rooster are up against.
https://www.backyardchickens.com/threads/mareks-long-term-prognosis.625129/
https://www.backyardchickens.com/th...-in-mareks-infected-hen.733001/#post-10184149
https://www.backyardchickens.com/threads/mareks-long-term-prognosis.625129/
https://www.backyardchickens.com/th...-in-mareks-infected-hen.733001/#post-10184149