What is the most likely diagnosis for a young female who developed a severe sore throat after stopping antibiotics for streptococcal pharyngitis?

In this scenario, the young female's development of a severe sore throat after stopping antibiotics for streptococcal pharyngitis strongly indicates the possibility of a peritonsillar abscess. This condition frequently arises as a complication of acute bacterial tonsillitis or pharyngitis, especially when the initial infection is inadequately treated or if there is a recurrent infection.

A peritonsillar abscess is characterized by the accumulation of pus behind the tonsil, leading to significant throat pain, difficulty swallowing, and potentially trismus (inability to open the mouth). The symptoms can be exacerbated following a recent throat infection, particularly if there was incomplete resolution of the initial illness.

In contrast, recurrent streptococcal pharyngitis would typically present with multiple episodes of throat pain but might not necessarily arise suddenly after stopping antibiotics. Infectious mononucleosis presents with additional symptoms such as lymphadenopathy, fever, and fatigue, and is most commonly associated with Epstein-Barr virus, not necessarily after antibiotic treatment. Gonococcal pharyngitis is a sexually transmitted infection that would have additional indicators, like a more varied clinical history or sexual exposure risks, that do not align here.

Thus, the context of recent antibiotic