I know that the head rotation would cause me to have problems. You could try a centerline swim snorkel. They make it so you can swim with little head movement.

I have had tinnitus for decades. It often never goes away. I don't even consider it a PCS symptom any more.

I find headaches can also be tied to quality of sleep. Our concussed brains are far more sensitive to sleep even after the other symptoms have resolved.

Anxiety from one symptom can cause the other symptom.

It is often trial and error that answers these questions. No hard and fast answers.