During the prodrome phase, you feel an episode coming on. Often marked by intense sweating and nausea—with or without pain in your abdomen—this phase can last from a few minutes to several hours. Your skin may look unusually pale. 

Click here to learn more about phases of CVS: https://www.niddk.nih.gov/health-information/digestive-diseases/cyclic-vomiting-syndrome/symptoms-causes