Hello apf'
As soon as I read your post with regard to intracranial pressure I immediately thought of residual shingle pain. I had shingles twice on my forehead and once on my back. I sometimes, not often, have a mild residual pain at the back of my head however so far not with all we do with and for Bronchiectasis.

I was curious after reading your post. I did google: can residual shingle pain in the head come and go with coughing up mucus and AI stated this:
Yes, postherpetic neuralgia (PHN), the lingering pain after shingles, can sometimes be triggered or exacerbated by coughing up mucus, especially if the shingles rash was on the head or face. PHN can be a constant pain, but it can also come and go, with various factors, including physical activity like coughing, potentially triggering or intensifying it."
Have you ever had a shingles bout at the head area??? You might want to do a deeper dive than I did and look further than what I did if you think this might be related to residual pain from shingles.
Barbara