It sounds as Twin is suffering from a gastrointestinal condition, possibly an infection. it could also be due to ingestion of a foreign body material. i would recommend taking her to the vet the first chance you get, she will need to be checked first, if the vet thinks it's a simple gastrointestinal infection she will need an anti vomiting injection, antibiotics and a special food for a few days in order to get better. if the vet thinks it is more serious she will need a blood test and possibly an ultrasound in order to find out what is wrong.