Shakiness and blurred vision are two classic symptoms of (reactive) hypoglycemia (low blood sugar). Some get these symptoms, some don't.
Have you had your grapefruit juice and fruit following your cleanse? These will help to raise your blood Sugar following your fast. If these take care of the problem, then you might want to get checked out for hypoglycemia, reactive or otherwise.
Also, the hypoglycemic reaction could be just a one time event evoked from the fasting, since you've been sick and all.
I hope you feel better. Let us know how you're doing...