The putrid smell makes it sound like a regurg since you fed 2 days ago. You also said she prefers the cool side and being she is 1700+ grams in a 28 qt tub she may not have adequate room to thermoregulate. Keep us posted, if she regurged, I would definitely work on upgrading her tub size. If its some other ailment taking her to vet sounds like a good idea. Hope everything works out.