get the shakes
To tremble or shake involuntarily, as due to fear, unease, anxiety, or a reaction to (or withdrawal from) a substance, such as caffeine, drugs, or alcohol. I've been doing public speaking for ten years, but I still get the shakes before going out in front of a large audience. I'm trying to get sober and haven't had a drink in four days, but I've been getting the shakes something fierce.