Jeanette is correct it could very well be Hypoglycemia (low blood sugar) that is causing it. It could also mean something else entirely. Signs (what you actually see) and symptoms (what you actually feel) of hypoglycemia.
Here are the signs and symptoms of hypoglycemia:
Adrenergic manifestations
Shakiness, anxiety, nervousness
Palpitations, tachycardia
Sweating, feeling of warmth
Pallor, coldness, clamminess
Dilated pupils (mydriasis)
Feeling of numbness "pins and needles" (paresthesia)
Glucagon manifestations
Hunger, borborygmus
Nausea, vomiting, abdominal discomfort
Headache
Neuroglycopenic manifestations
Abnormal mentation, impaired judgment
Nonspecific dysphoria, moodiness, depression, crying, exaggerated concerns
Negativism, irritability, belligerence, combativeness, rage
Personality change, emotional lability
Fatigue, weakness, apathy, lethargy, daydreaming, sleep
Confusion, amnesia, dizziness, delirium
Staring, "glassy" look, blurred vision, double vision
Flashes of light in the field of vision
Automatic behavior, also known as automatism
Difficulty speaking, slurred speech
Ataxia, incoordination, sometimes mistaken for "drunkenness"
Focal or general motor deficit, paralysis, hemiparesis
Paresthesia, headache
Stupor, coma, abnormal breathing
Generalized or focal seizures
Dysmenorrhea
Only a doctor can accurately diagnose hypoglycemia (or any other problem accurately) through a series of tests. Other things to consider are age, weight, male or female, familial (family) history, stress levels, other medications, etc.
In other words you may be fine after eating (curious as to what is your meal schedule) may not have any other symptoms and have hypoglycemia or pre-diabetes. Only your doctor will be able to tell you.
Though, I doubt Parkinson's, and again only doctors tests will confirm, or even deny; I do know that Michael J. Fox had a problem during the filming of Doc Hollywood. One of his index fingers wouldn't stop twitching. Think it was a pinched nerve he went to the doctor at the conclusion of filming. It took a full-year to properly diagnose Parkinson's.
Since this is rather long - I recommend that you don't wait get seen by a doctor.
Take care,
Stargazer