Sometimes it can just be anxiety. It could also be a thyroid problem or Diabetes. In any case, you should see a doctor and have it checked out.
Things like this can happen to anyone, no matter how healthy.
headaches can be caused by constriction of blood flow in the brain, and sudden causes maybe down to dehydration
It causes tornadoes
causes of frequent nausea and vomiting
A mental disease
There are several causes of sudden water retention. Poor circulation, premenstrual symptoms, salt, or a blockage in the lymphatic system can all cause this condition.
a surge of testosterone in males and it causes ovulation in females.
It causes and earthquake
sudden submarine earthquakes
natural causes or hunted or sudden death
A shock is something which causes sudden, heavy impact, a sudden electrical charge, or an amount of considerable emotional impact.
I would ask your vet but that sounds like Parvo
it is EARTHQUAKES