COVID-19: Given the patient's symptoms of fever, chills, dry cough, arthralgia, and erythematous rash, along with his occupation in a hospital which increases his risk of exposure, COVID-19 is a highly plausible diagnosis. The elevated CRP and WBC count also support an infectious process.

Influenza: Similar to COVID-19, influenza can present with fever, chills, cough, and body aches. The presence of an erythematous rash, although less common, does not rule out influenza.
Hospital-acquired Infections (e.g., MRSA, C. difficile): Working in a hospital setting increases the risk of acquiring nosocomial infections. While the symptoms could fit, the absence of specific indicators like diarrhea (for C. difficile) or a clear source of infection (for MRSA) makes these less likely but still possible.
Viral Exanthems (e.g., measles, rubella): Although less common in adults, especially those vaccinated, viral exanthems can cause fever, rash, and systemic symptoms. The dry cough and specific occupation might lean more towards other diagnoses, but they remain in the differential.

Meningococcemia: This condition, caused by Neisseria meningitidis, can present with fever, rash, and rapidly progressive shock. It's critical to consider due to its high mortality rate if not promptly treated. The patient's occupation in a hospital and the presence of an erythematous rash necessitate its inclusion in the differential.
Toxic Shock Syndrome: Caused by bacterial toxins, typically from Staphylococcus aureus or Streptococcus pyogenes, this condition can present with fever, rash, and multi-organ involvement, including renal impairment as suggested by pre-renal AKI.
Sepsis from Other Causes: Sepsis, regardless of the causative agent, is a life-threatening condition that requires immediate recognition and treatment. The patient's symptoms of fever, chills, elevated WBC, and organ dysfunction (pre-renal AKI) could be indicative of sepsis.

Rickettsial Diseases (e.g., Rocky Mountain Spotted Fever): These diseases, transmitted by ticks, can cause fever, rash, and systemic symptoms. While less likely given the patient's occupation and lack of specific exposure history, they should be considered in the appropriate clinical context.
Ehrlichiosis/Anaplasmosis: Similar to rickettsial diseases, these tick-borne illnesses can present with fever, rash, and systemic symptoms, including elevated liver enzymes and low white blood cell count, though the latter is not present in this case.
Adult-Onset Still's Disease: A rare autoimmune condition characterized by high fevers, salmon-colored rash, and arthralgias, among other symptoms. It's a diagnosis of exclusion but should be considered if other, more common diagnoses are ruled out.