Hi, usually if there is any reaction due to Covid vaccination, it won't last more than 48 hours. Since you have mentioned it's already been 4 th day since vaccination and also the you have been having high grade fever, kindly consult a physician near your place for clinical examination and evaluation of fever and to Check the Injection site for any abscess formation.
Just paracetamol may not be sufficient.
Next Steps
consult a General Physician near your place.
Health Tips
Adequate Hydration is important.