Fluctuating symptoms, aka the roller coaster, is very common for PCS. I find it "odd" that he doesn't know that. Then again, we probably know more about concussion/TBI than most doctors just from reading this forum.
It comes and goes for me too. It's much worse when I'm under stress or if my brain is flooded from overstimulation. Just the other night, I spit on the ground in front of a store and the security guard almost stepped in it, so I said "Careful not to spit...sit...STEP in it".
Ugh, it's embarrassing. But...what can we do???
As you can see...you're not alone. So I hope just knowing that will make you feel a little better.
Peace,
Nick