Hello there, your mother's
tsh level is below the normal range but it varies from lab to lab.
Kindly share the details of the lab report in chat. Its not advised to titrate the dose of thyroxine suddenly as it takes months to titrate the dose.
The joint pain fever and cough cold suggest another disease process and I would recommend consulting a doctor.
Next Steps
Kindly consult a doctor. I myself am available here on practo for consult.
Health Tips
Do not change the dose of the drug without consulting a doctor.