1
I feel sick; I think I'm going to vomit.
Start by signing 'I', 'feel', and 'sick', then transition smoothly into the 'vomit' sign, adding a slightly distressed or nauseous facial expression to match the context.
2
The dog ate too much and vomited.
Sign 'dog', 'eat', and 'too much', and then use the sign for 'vomit', making sure to move both hands outward from the mouth to show the action.
3
Please clean up the vomit on the floor.
Point to the area, sign 'vomit', and then use the sign for 'clean'. Your facial expression can show mild disgust to emphasize the unpleasantness of the mess.