Hi,
I was a competitive cyclist and also involved in playing guitar and singing pre concussion. Singing after was also hard for me. It created tension in base of skull and triggered a migraine a couple times. 20 months after though, I started practising again - both playing guitar and singing. It was tough at first, but 8 months later and I'm good to go with singing. I still have other symptoms, but feel about 90% recovered overall.

As for exercise, it's supposed to help, but for me it was a choice of cashing my available energy chips on earning a living, or exercise - doing both is still very tough to manage as I burn out, even 2.5 years after the concussion.

I've heard playing music is very stimulating for the brain, so maybe good "exercise" for it?