I was put on antibotics for a jaw infection. Since then I have retained a fever, fainted, and feel nauseous and sleepy. Could this be an emergency?

Get checked out! All the things you describe aren't good signs of healing. We typically expect a person's temperature to improve after starting antibiotics. The nausea could be a side effect of the antibiotics, but feeling sleepy and fainting could be the infection getting worse. Talk to your doctor asap. Meaning today. If you can't get ahold of your doctor for whatever reason - go to an urgent care or ed.