I have a very, very bad sore throat, a fever consistently between 99-101 degrees, a headache, a slight cough, and a stuffed nose it all came on quite suddenly on sunday. What could this be?

Cold or flu. Cold or flu would be the most likely answer. It worsens or continues, see an md. Good luck.
Based . Based on the symptoms you described you could be dealing with pharyngitis (infection of the throat) which could be caused by a bacterial or a virus; versus a sinus infection. Other more serious less likely possibilities include influenza (flu) or meningitis (infection of the central nervous system). Regardless, you need to see your health care provider right away; the provider will ask you specific questions about your illness and perform a physical exam. You can expect that your provider will likely perform a throat culture or a test called a rapid strep test and possibly blood tests to check for certain infections. Your doctor/provider will make a decision based on the test results regarding which treatment is appropriate. If a more serious problem is suspected, your doctor will likely send you to the emergency department.