What does it mean if i have cough and fever?

Breathing problems: If you are experiencing cough associated with significant fever, you may very well have pneumonia, and that will require an antibiotic. Other potential causes include a blot clot in the lung, tumor, and other inflammatory conditions of the lung. So, yes, it could be something bad. Best to have it checked out.

Infection: You may have an upper or lower respiratory tract infection. If your symptoms include shortness of breath and chest pain you should see the doctor.