61 years has the half body sweating,the left side, cold sweat,often duringthe night but sometimes during the day.after sweating feels sluggish,what is?

Harlequin syndrome: Changes in a person's normal pattern of sweating can have many causes: medications, & hormonal imbalance, etc., which are easily treatable. Sweating on one half of the body can also be a symptoms of Harlequin syndrome, arachnoiditis and other disorders of the nervous system. These are rarer and may be more serious. Please see a doctor as soon as possible to determine the cause in your case,