Was she tested COVID positive? Weakness is a common after effect of this disease, there are different ways of overcoming the weakness but they need to be carefully defined for the patient. For example we will need to understand if she is diabetic or not or has any hypertension? I would suggest you consult a doctor properly and then get guidance on medication.
Next Steps
To consult: https://www.practo.com/meerut/doctor/rajesh-kumar-gupta-general-physician-1