What is the diagnosis and treatment plan for a 29-year-old active duty male with a 3-week history of chest tightness, dyspnea (difficulty breathing), cough, fatigue, hot and cold spells, diarrhea (loose stools), bilateral temporal headaches, loss of appetite, tachycardia (high heart rate), and muscle tightness in the neck and shoulders, who recently traveled and has a history of exposure to household members with a cough, and presents with abnormal physical exam findings including erythematous (red) ears, mildly bloody nose, white pus-like lesions on the mouth, and tender anterior cervical lymph nodes?

Diagnosis: Viral Respiratory Infection with Gastrointestinal Manifestations

This 29-year-old presents with a classic viral respiratory infection, most likely COVID-19 or another respiratory virus, given the characteristic pattern of gastrointestinal symptoms (diarrhea, fatigue) preceding respiratory symptoms (cough, chest tightness) by approximately 3 weeks, combined with pharyngitis findings and recent household exposure to cough illness. 1

Immediate Diagnostic Steps

Priority Testing

• Obtain COVID-19 RT-PCR testing immediately given the temporal pattern of GI symptoms preceding respiratory manifestations, which occurs in 3.2% of hospitalized COVID-19 patients 1
• Chest radiograph is mandatory to evaluate for pneumonia given the chest tightness, dyspnea on deep inspiration, and 3-week symptom duration 1
• Check vital signs including oxygen saturation and assess hydration status from the ongoing diarrhea 1

Physical Exam Findings Analysis

The constellation of findings points toward viral pharyngitis with systemic involvement:

• Erythematous oropharynx with white exudative lesions bilaterally suggests viral or bacterial pharyngitis 1
• Tender anterior cervical lymphadenopathy supports infectious etiology 1
• Erythematous external ears may indicate systemic inflammatory response 1
• Hyperactive bowel sounds with diarrhea (3 loose stools daily for 3 weeks) consistent with viral gastroenteritis 1
• Clear lung fields make bacterial pneumonia less likely but do not exclude viral pneumonia 1

Infection Control Measures

If COVID-19 is suspected, implement immediate isolation precautions: provide surgical mask, use appropriate PPE, isolate in negative pressure room if available, and maintain staff contact list 1

Treatment Plan

For Gastrointestinal Symptoms

• Oral rehydration therapy is the cornerstone for the diarrhea component, which has a median duration of 4 days in viral infections 1
• Do not prescribe empirical antibiotics unless signs of invasive bacterial disease develop (bloody diarrhea, high fever, severe systemic toxicity) 1
• Most viral diarrhea is self-limited 1

For Respiratory Symptoms (Subacute Postinfectious Cough)

This represents a subacute cough in the postinfectious category given the 3-week duration 1

First-line treatment:

• Start first-generation antihistamine/decongestant combination (e.g., brompheniramine/pseudoephedrine) once daily at bedtime, then advance to twice daily if needed 1
• Add intranasal corticosteroids (e.g., fluticasone, mometasone) to decrease airway inflammation, particularly given the nasal symptoms (mildly bloody nose suggesting mucosal irritation) 1

For Pharyngitis

• The white exudative lesions with erythematous oropharynx warrant consideration of rapid strep testing or throat culture to rule out Group A Streptococcus, despite the viral presentation being more likely 2
• If strep negative, supportive care with analgesics and throat lozenges 2

Symptomatic Management

• Acetaminophen or NSAIDs for headaches, myalgias (neck/shoulder tightness), and fever 1
• Adequate hydration for both respiratory and GI symptoms 1
• Rest and activity modification given the fatigue 1

Red Flags Requiring Immediate Escalation

Escalate immediately if any of the following develop:

• Dyspnea, hypoxemia (SpO2 <94%), or respiratory distress 1
• Bloody diarrhea, signs of severe dehydration, or inability to maintain oral hydration 1
• High persistent fever (>102°F for >3 days), severe systemic toxicity, or hemodynamic instability 1
• Worsening chest pain or tachycardia 1

Follow-Up and Monitoring

• Reevaluate within 7-10 days if symptoms fail to improve or worsen 1
• Most postinfectious coughs resolve within 3-8 weeks without specific intervention beyond symptomatic management 1
• If cough persists beyond 8 weeks, systematic evaluation for chronic cough causes becomes necessary, including upper airway cough syndrome (UACS), asthma, non-asthmatic eosinophilic bronchitis (NAEB), and gastroesophageal reflux disease (GERD) 2, 1

Critical Pitfalls to Avoid

• Do not dismiss the temporal pattern of GI symptoms preceding respiratory symptoms—this is characteristic of COVID-19 and warrants testing 1
• Do not prescribe antibiotics empirically for the diarrhea or cough without evidence of bacterial infection 1
• Do not overlook dehydration assessment given 3 weeks of diarrhea (3 stools/day) 1
• Do not assume clear lung sounds exclude significant pulmonary pathology—chest radiograph is still indicated given the symptom duration and dyspnea 1
• Consider strep pharyngitis despite viral presentation being more likely, as the exudative pharyngitis warrants testing 2

Expected Clinical Course

The median duration of diarrhea in viral infections is 4 days, though this patient's has persisted for 3 weeks, suggesting either ongoing viral shedding or a different etiology that should be monitored 1. The cough typically resolves within 3-8 weeks with symptomatic management 1. If symptoms persist beyond expected timeframes, reassess for alternative diagnoses including uncommon causes of chronic cough 2 or complications.