Thank you for your query on Healthcare Magic.
The reason for her salivation and decreased oral intake is due to presence of ulcers in her mouth.
If she is not accepting the antibiotic syrup, consult the doctor again for modification of the drug if required.
Give very soft diet
and plenty of oral fluids to drink.
You can apply an oral local anesthetic
gels like benzocaine
on ulcers before food with the doctor advise for pain relief and acceptance of food.
Hope I have answered your query.