your symptoms description is pointing towards parotitis in easy language गलसूया . It is self limiting viral infection but u need to start her on tab clindamycin antibiotic , one anti inflammatory and a multivitamin just to avoid super added infection. you can do hot compress over the swelling and can apply magsulf ointment twice a day dont use belladona patches. Maintain hydration as much as possible and should avoid cold and sour food.
Next Steps
If kids and elders at home , do ask her to wear mask as it gets transmitted easily