Differential Diagnosis
- Single most likely diagnosis
- Scarlet fever: This condition is characterized by a sandpaper-like rash, which is consistent with the patient's symptoms. The history of strep A infection, which was treated with amoxicillin, also supports this diagnosis. However, the persistence of sore throat and development of mouth ulcers could indicate a complication or incomplete treatment.
- Other Likely diagnoses
- Infectious mononucleosis (mono): This condition can cause persistent sore throat, fatigue, and mouth ulcers, which align with the patient's symptoms. Although the patient was treated for strep A, mono can sometimes be misdiagnosed as strep throat.
- Strep throat complication (e.g., peritonsillar abscess or streptococcal toxic shock syndrome): Despite treatment with amoxicillin, the patient's persistent sore throat could indicate a complication of strep throat.
- Viral pharyngitis: This condition can cause sore throat, mouth ulcers, and fatigue, and may have been misdiagnosed as strep A initially.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Lemierre's syndrome: This rare but life-threatening condition is characterized by a sore throat, followed by neck pain and swelling, and can lead to sepsis. Although it is unlikely, it is crucial to consider due to its high mortality rate.
- Epiglottitis: This condition can cause severe sore throat, difficulty swallowing, and shortness of breath, and requires prompt medical attention to prevent airway obstruction.
- Rare diagnoses
- Kawasaki disease: This rare condition can cause a rash, fever, and mouth ulcers, but is typically seen in children under the age of 5.
- Stevens-Johnson syndrome: This rare but serious condition is characterized by a severe rash, mouth ulcers, and eye inflammation, and can be life-threatening if not promptly treated.
- Pemphigus: This rare autoimmune disorder can cause mouth ulcers and a rash, but is typically seen in older adults.