As more patients recover from COVID-19 infection, long-term complications are beginning to arise. Our case report will explore a debilitating long-term complication, Post-COVID Interstitial Lung Disease (PC-ILD). We will introduce a patient who developed PC-ILD in the setting of diffuse large B-cell lymphoma, outlining a difficult hospital course, including a positive COVID-19 polymerase chain reaction (PCR) for more than 3 months. We will then discuss the human body's physiological response to the virus and how our patient was not able to adequately mount an immune response. Finally, the pathophysiology of PC-ILD will be explored and correlated with the patient's subsequent computed tomographic images obtained over a 3-month period. The difficult hospital course and complex medical decision-making outlined in this case report serve as a reminder for health care providers to maintain vigilance in protecting our most vulnerable patient population from such a devastating disease process.