Hi Russell -
I may be over-thinking this, but if you think I may be in th Dark Night, armed with this knowledge and never doing insight practice, how would I go about pushing through this phase?
Have you read the [url=http://web.mac.com/danielmingram/iWeb/Daniel%20Ingram's%20Dharma%20Blog/The%20Blook/740E1DCD-75A5-4859-8530-13214BE1BA33.html]Mastering the Core Teachings of the Buddha chapter 25 on Stages 5-10?
If not, maybe have a close careful read and see what you think.
I will say that the crest of my "dark night" experience was characterized by physical sickness, and, like you, I found tibetan guidebooks at about the same time - but felt too sick and was sleeping all the time with a constant low fever to read the books with any consistency. I made similar dietary changes as you, and then I realized I needed to tackle anxiety.
Keep in mind that anxiety forms a neurological loop feeding itself ("HPA disregulation") - if you do not actively start cutting back at it, it grows to fill one's time. Exercise that increases heart rate for a bit is very helpful (swimming, running) - exercise is THE first macro tool I would use on anxiety. You might check out J. Medina's book "Brain Rules", too, or excerpts from his book online. Consider a Tibetan buddhist view of karma - karma simply describes a matter of perspective: what you perceive now is what you will perceive in the future; if anxiety is allowed to color your perception now, your perception in the future will be colored by anxiety.
Apply toe tibetan concept of "emaho" (sanskrit for "delight and wonder") - consider spending no less than five minutes a day in a pleasant place apply emaho perspective (cultivate delight and wonder).
Thereafter or in conjunction with exercise, there are many fine tuning things to do (slow traditional stretching yoga (not so much the strengthening yoga at the beginning and not the "flow" yoga popular in the West these days as that involves lots of muscle contractions versus slow stretches which allow for muscle spindle release. Here is THE dude, Ray Long MD, for getting into classic yoga with body awareness and spindle utility -
this page's description of Uttanasana is simple and beautiful. Stay very gentle-no ego with yourself. If you can relax into stretches for two minutes (or approach two minutes over a period of days) and use your breathe to stay in gentle, active effort and to focus your mind, then two minutes is generally how much time the muscle spindles need to do their release from contraction (and you get to feel goooood). Long slow deep breathes. Gentle. You don't even need "yoga", just stretch your body in ways you can sustain with comfortable effort and deep breathing for about two minutes (4 simple yoga poses for a total of 10 minutes: downward facing dog, cow-cat, Ardha Matsyendrasana - you be your own expert, but you can read about these on Yoga Journal.)