Re: Chrisb1 Question:

Mighty,
good to hear that your vital signs are fine.

In answer to your questions..........

Crises can last for varied amounts of time so difficult to say, but nausea can be caused by a lowering of the tension within the stomach: anxiety, stress, and worries can also exacerbate this issue.
No real definitive answer here I'm afraid.

How good should you feel before breaking the fast?

I can do no better than quote..............
Carrington, when he states as the ideal time when breaking the fast............................
"A sudden and complete rejuvenation; a feeling of lightness, buoyancy, and good health steals over the patient in an irresistable wave; bringing contentment and a general feeling of well-being, and of the possession of a superabundance of animal spirits."

Extreme weakness and dizziness is most definitely a period when you should have absolute rest...............
"Persistent extreme weakness is more likely to prove a danger signal, although this is so rare that I have seen but one such case".....SHELTON.

In other words, if the weakness is prolonged, or becomes progressively worse I would terminate the fast.

In what way are you feeling weak? and how does this affect your physical mobility?

Nausea can also make you feel weak as well, so if and when the nausea subsides, you will most likely feel stronger.

Chrisb1.