It sounds to me like some kind of seizure. i know people generally think of seizures in terms of strong muscular contractions, but there are actually numerous times of seizures. Some seizures have no muscle contraction involvement.
The other clue that makes me think it is possibly a form of seizure is the statement you made that alcohol helps it. Alcohol is a sedative because of its action on the brain's GABA. And GABA inhibits seizures.