I can take many people a year or more to taper comfortably from Ativan and other benzos without longterm uncomfortable side effects and even seizures. Individual reactions could vary widely. Over at BrainTalk there is a lot of discussion of benzo withdrawal.
Symptoms of Ativan withdrawal include anxiety, insomnia, muscle spasms, seizures, weight loss. The symptoms you describe are not specific for Ativan withdrawal, but if they resolve in a few days, that may be the answer. If these symptoms persist then you should contact your doctor immediately.