My panic attacks always include involuntary movement or shaking of limbs hands head etc. so to me it sounds like the beginning of panic starting. Try to concentrate on one thing in detail. Taking a drink of water, first concentrate on your hand movement to the glass making sure it does not shake (it helps to stiffen/flex the muscle), grabbing the glass, lifting the glass, getting it to your mouth, drinking, then setting it back down. break down the movement in simple steps while concentrating on keeping your hand shaking to a minimum. hope that makes sense its like baby steps