Recurrent Malignant Otitis Externa: Given the patient's history of malignant otitis externa, a recurrent infection is highly plausible, especially considering the worsening symptoms over seven days. The feeling of a clogged ear and the absence of systemic symptoms like fever or chills do not rule out this condition, as it can present with a range of severity.

Chronic Otitis Externa: This condition could explain the patient's symptoms of a clogged ear and is a common issue in individuals with a history of ear infections. It might not be as severe as malignant otitis externa but could still cause significant discomfort and require medical attention.
Earwax Impaction: This is a common condition that can cause a feeling of fullness or blockage in the ear. Given the patient's age and history of ear issues, it's possible that earwax has accumulated and is causing his current symptoms.
Middle Ear Effusion: This condition involves fluid accumulation in the middle ear and can cause a sensation of fullness or blockage. It might be a complication of an upper respiratory infection or Eustachian tube dysfunction, which could be more prone in someone with a history of ear infections.

Necrotizing Otitis Externa: Although the patient has a history of malignant otitis externa, necrotizing otitis externa is a more severe form that can lead to significant complications, including cranial nerve paralysis and death if not promptly treated. The absence of fever or chills does not rule out this condition.
Petrous Apicitis: This is a rare but serious infection of the petrous part of the temporal bone. It can present with otitis externa symptoms and is crucial to diagnose early to prevent severe complications.
Skull Base Osteomyelitis: This condition is a rare but potentially life-threatening complication of otitis externa. It involves infection of the bones at the base of the skull and requires prompt diagnosis and treatment.

Relapsing Polychondritis: This is an autoimmune condition that can cause cartilage inflammation, including in the ears. While rare, it could potentially cause symptoms similar to those of an ear infection.
Eosinophilic Otitis Media: This condition is characterized by an eosinophilic infiltration of the middle ear and is often associated with asthma or other atopic conditions. It's a rare cause of ear symptoms but should be considered in patients with atopic histories.