How come if I stop drinking soda for a day, I get hot and sweaty?

Withdrawal. Please see here for some information on withdrawal from soda. http://www.caffeineinformer.com/caffeine-withdrawal-symptoms-top-ten.
Psychological depend. Dependency on any food,smoking and drugs causes anxiety and stress when the objects are not available. It could also be possible that you develop hypoglycemia due to hyperinsulinemia from insulin resistance which could cause the symptoms when you do not drink soda.