Hi, your mother could either have an infection like mumps which infection the glands and cause swelling or the joint around the jaw called temperomandibular joint could be causing the issue. You need to get a video consultation with a physician at the earliest. You can give your mother painkiller to reduce pain while eating if the pain is unbearable.

Rest when you feel weak or tired. Take over-the-counter pain relievers, such as acetaminophen and ibuprofen, to bring down your fever. Soothe swollen glands by applying ice packs. Drink plenty of fluids to avoid dehydration due to fever. It may be mump for proper treatment -need history and evaluation -u can consult me online for treatment here or on whatspp 87 07 81 33 one eight

Requires video calling to assess the swelling ,then age of the patient her body built ,many more things needs to be assessed to arrive to diagnosis .

Need detailed history and evaluation

Consult with dentist, and take zerdol-s for pain and swelling.