Thanks for providing more information.
A sudden significant weight gain can be a sign of a very serious issue as in, if she is suddenly gaining a significant amount of weight overnight or over a few hours) which is related to water retention and caused due to heart/kidney disease which may require an urgent medical attention.
So i agree with you that she needs to be seen by a doctor at ER ASAP.
Other potential differential diagnosis may include Hormonal imbalance,Thyroid dysfunction,Paxil side effect.
First heart function needs to be assessed.
If any problem an echo cardiogram needs to be done.
Work up must include her blood sugar, cholesterol tests, thyroid function,female hormones, adrenal function and kidney functions. Her abdominal / pelvic ultrasound would be done.
Hope this helps.
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