Withdrawal symptoms. Probably the most serious alcohol withdrawal would be delirium tremens, a state where a person is delirious and even hallucinates and temperature, blood pressure & heart rate go up & can be fatal without proper care. Other symptoms like agitation & tremors (twitching) may lead to grand mal seizures also quite serious. These are serious & need intervention since they can become severe in 24/48 hrs.
Might be DT's. Severe twitching in an alcoholic who recently stopped drinking could be from delirium tremens, or "dt's." it is one of the few medical emergencies in drug withdrawal. Unlike opiate withdrawal, dt's can actually cause death in about 5% of patients. It is typically associated with very high bp, rapid heart rate and even hallucinations. Those with possible dt's should seek medical treatment asap!