I get muscle spasms or twitch all over my body all day and night long for almost two years now..what is the cause and how to treat the problem?

Fasiculations: Twitching of muscles can have many causes - many will not be mentioned here. Withdrawal from medications, restless leg syndrome, metabolic imbalance (low calcium, magnesium, others), seizures, tetanus, dystonic reaction from medications like antipsychotics, reglan, (metoclopramide) or anti-nausea agents, certain neurological conditions. The treatment depends on the disease. You should consult with your doctor.

Complex: The cause of "spasms" could range from benign causes to significant neurological problems. Benign myoclonus is one condition that is more of a nuisance whereas a myocloic epilepsy or other metabolic disorder could be a more worrisome cause. The treatments vary widely based on the cause. You should be evaluated by a neurologist.