I too have been curious about "shadows", ironically, I just wrote this update to my family yesterday:
"I still feel, what I call, 'tinges' of headache pain that typically coincide with the timing of what would be an attack, so 'The Beast' is letting me know he’s still hanging out, probably pissed off he’s had to sit on the sidelines while the steroids are getting all the attention. Hopefully, he won’t be ready to go full beast-mode on my dome when the steroids wear off."
Thanks for connecting the dots Spiny!