She could have reflux. The warm water is relaxing her stomach and it's not clenching from getting non-warm fluids.
She may need to do an X-ray test for reflux. We gave our little guy almost a full syringe of Reglan about 10 minutes before each feeding. It relaxes the muscles in the stomach and helps the bottom open up so the food passes through into the intestines quicker. If they do have spasms then some of the food is already being processed down below the stomach.
I hope you get a gasro doc on board very quickly. Little ones like this can go downhill quickly. If she is not peeing or pooping a lot you need to see a doc now.