Differential Diagnosis

The patient presents with a complex array of symptoms, including fever, upper right quadrant pain, fatigue, brain fog, rash on tattoos, joint pain, muscle pain, and gastrointestinal symptoms, among others. Given the patient's history and laboratory results, the following differential diagnoses are considered:

• Single Most Likely Diagnosis
  • Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME): This condition is characterized by persistent fatigue, muscle pain, joint pain, and cognitive difficulties, which align with many of the patient's symptoms. The recent COVID-19 infection could be a triggering factor, and the presence of slightly elevated WBC and positive EBV antibodies (indicating past infection) supports an immune system dysregulation.
• Other Likely Diagnoses
  • Autoimmune Hepatitis: Despite normal liver function tests, the upper right quadrant pain and other systemic symptoms could suggest autoimmune hepatitis, especially in the context of Hashimoto's thyroiditis and suspected Ehlers-Danlos syndrome, indicating a predisposition to autoimmune conditions.
  • Sjögren's Syndrome: This autoimmune disorder can cause fatigue, joint pain, and gastrointestinal symptoms. The itchy armpits and rash on tattoos could be indicative of skin involvement, and the presence of another autoimmune condition (Hashimoto's) increases the likelihood.
  • Fibromyalgia: Characterized by widespread muscle pain, fatigue, and cognitive difficulties, fibromyalgia could explain many of the patient's symptoms. The asymmetrical joint pain and muscle weakness are particularly suggestive.
• Do Not Miss Diagnoses
  • Lymphoma: Although less likely, given the lack of significantly abnormal CBC results, lymphoma must be considered due to the persistent fever, night sweats (implied by chills), and weight loss. The elevated lymphocytes also warrant careful evaluation.
  • Systemic Lupus Erythematosus (SLE): This autoimmune disease can present with a wide range of symptoms, including fever, joint pain, rash, and gastrointestinal issues. The presence of Hashimoto's and suspected Ehlers-Danlos syndrome increases the risk, and SLE can be life-threatening if not recognized and treated.
  • Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease or ulcerative colitis could explain the gastrointestinal symptoms, weight loss, and systemic inflammation. The upper right quadrant pain could be related to the liver or biliary system involvement sometimes seen in IBD.
• Rare Diagnoses
  • Mast Cell Activation Syndrome: This condition involves the accumulation of mast cells in various tissues, leading to symptoms like hives, itching, flushing, and gastrointestinal issues. The itchy armpits, rash on tattoos, and gastrointestinal symptoms could be indicative of mast cell activation.
  • Ehlers-Danlos Syndrome-related Complications: While suspected, the diagnosis of Ehlers-Danlos syndrome itself is not a condition causing the current symptoms but recognizing its potential complications (e.g., gastrointestinal, autonomic dysfunction) is crucial for comprehensive management.

Each of these diagnoses requires careful consideration of the patient's complex clinical presentation, and further diagnostic testing or specialist consultation may be necessary to determine the underlying cause(s) of the symptoms.