Dear Stefan,
Your question seem to have 2 parts, one theoretical and one practical.
Since it appears to me that you're concerned more with a practical answer I'll only relate how I handled this situation in 2 practical instances some years ago. And only state where the theory would let to wrong conclusions in how to be with such situations.
I don't give advise directly, but advise to decide on a case to case basis oneself. For the simple reason that different teachers saw it contrary in specific cases, and if you depend on answers you could get really confused.
The yardstick given by Goenkaji to make this method work is:
'awareness and equanimity with sensations in the knowledge of their impermanence have to be sustained'And NOT to desolve the pain, on the contrary, if you continue this method it will bring you to a place where you will experience all-pervaiding Dukkha!
1) Very strong toothpain: in this case I realized that by moving with awareness of sensations through the body I lost my equanimity, as if moving away from my mouth made the pain there so strong making me fail in fullfilling above maxim.
And always arriving at the pain equanimity could be maintained again.
So - after many hours keeping strictly to the instructions to move - I finally remembered Goenka's maxim and stopped at the pain itself. Within one sit it was gone.
2) Very, very strong chronical back pain: before in life I never took painkillers but just took the pain instead.
But then I got a spine-infection which made me immoveable and binded to bed for altogether 8 months. And at times I couldn't maintain equanimity with the pain and very high doses of painkillers available at that place (Bodhgaya). At its worst, even with the painkiller I was in agony, where I took every 4 hours a dose - still beginning with the 4th and ending with the 1st hour of the intake - I only could help myself with hyperventilation, moaning and groaning.
What to do is such situations? - My answer to myself at that time - be friendly and at ease with the impermanence of equanimity too.
Welcome to MAHA DUKKHA
