Gastroenteritis. Soda is a carbonated drink and drinking it when your stomach is not feeling well will cause you to vomit. That's because soda produces more gas in the stomach. Drain the soda in a cup and stir it to release the fizz before you drink it - then it might help prevent nausea and vomiting and prevent dehydration.
Try non-carbonated. Start w clear liquid like water, slightly flattened soda that is clear, or sports hydration drinks. Sip, sip, sip. Work up to solids w bland foods like bananas, rice, applesauce, toast, gelatin, or chicken. Avoid alcohol, nicotine, caffeine, dairy & high fat foods. Rest.
See below. The temperature really does not matter.
Either but. Traditional Chinese Medical recommendation would be tepid/ room temp.