Hello, this can be due to infection, i would suggest you to get a cbc done along with the chest xray, and if it's from more than 2 weeks get a sputum test done too, if the Fever rises in evening along with cough and associated with weight loss it can be tuberculosis otherwise just bacterial infection thus to rule out the cause get the investigation done
Next Steps
Get a Cbc done
Get a Chest xray done