Antibiotics n painkillers mostly wil not b the reason for weakness might b coz of tooth ache she is unable to eat or chew food ...any other underlaying condition ?? What all tablets she is using ?? detailed history is required as she is elderly female.
Next Steps
online consultation for better understanding of condition and to prescribe medications
Health Tips
avoid painkillers unless important
give soft n mashed food and diet which she can chew easily .
plenty of oral fluids, juices
cut down salt intake.