J,
First, of all, I want to express my empathy for your experience, it's a tough one. I feel for you because I have also had a lot of physical manifestations during my dark night. Although these manifestations are experienced physically, they are actually manifestations of consciousness being expressed through body sensations, muscle tension, and movement. There were times when I saw my body to be de-composing in to ashes in front of my open eyes, and times when I was utterly convinced that I had stopped breathing and was going to suffocate to death. Finally, I have experienced all kinds of extreme physical pressures felt inside my body. If the pressure is painful and solid feeling, then it's stage 3. If the pressure is moving around, squeezing or expanding, etc. Then it's one of A&P, fear, misery, disgust, or re-observation (squeezing in a vice grip sounds like re-observation to me). If you are caught in fear, adopt a tough guy attitude and basically dare the fear to get even worse. That resolves it faster than anything else I've tried.
One thing I've found very helpful if physical symptoms become too intense is to lie on a soft mattress and let my whole body spontaneously shake for as long as it needs to. This really tends to calm down the feeling of extreme internal pressure.
Another strategy that I've adopted recently is based on the realization that consciousness can express itself through any modality. Since body pressure and movement is a particularly unpleasant modality often, I've worked to transfer the expression of consciousness to the inner visual field (mind's eye). Here's how to do it. When you begin to experience a physical symptom like cranial squeezing, focus on this while also consciously resolving to experience
this very same sensation in the visual field. You might, for example start to see a hard rock being bashed repeatedly into your skull or something like that. Go with the imagery that comes naturally, and don't worry that it's "really" happening (it's not happening on the physical level). Just watch it and try to to dissolve the visual image into impermanence, and non-separateness. For example, if you see a rock basing into your skull, you'd watch attentively and notice how the rock keeps moving, and the "camera angel" won't stay still, that's impermanence starting to show up. Also, if the rock breaks the skull up into little pieces of bone and flesh (more impermanence), keep watching the little pieces until they turn into ash or insects or something like that, and then finally, keep watching until those little things until they dissolve into flickering particles. This might look like a bunch of little balls appearing and dispersing, or fluctuating waveforms, or TV screen static or something like that. Then you'll really be at the bottom of it, and you can go back to observing the bare sensations. In terms of the third characteristic, you might see the rock fall to pieces and sort of merge with the broken pieces of the skull. Also, sexual imagery often shows up in the mind's eye when you focus on the third characteristic, sometimes this may be disturbing, but again, go with it and focus on seeing it as a manifestation of the third characteristic.
Those are all just examples. You'll see what you'll see, but that gives you a sense for how it goes.
Best of luck, keep us updated.
Avi
Toronto Spiritual Direction