Acute Bacterial Infection: This is the most likely diagnosis given the combination of para abscess, pansinusitis, and mastoiditis. These conditions often result from bacterial infections that spread from the sinuses to surrounding tissues, including the mastoid bone and soft tissues of the face and neck.

Chronic Sinusitis with Acute Exacerbation: Chronic sinusitis can lead to complications such as pansinusitis and, if the infection spreads, mastoiditis and para abscess formation.
Invasive Fungal Sinusitis: Though less common, invasive fungal sinusitis can cause similar symptoms, especially in immunocompromised patients, and can lead to serious complications if not promptly treated.
Tuberculous Osteomyelitis: Although rare, tuberculosis can cause osteomyelitis of the mastoid and sinusitis, presenting with similar symptoms.

Cavernous Sinus Thrombosis: A potentially life-threatening condition that can arise from the spread of infection from the facial or sphenoid sinuses to the cavernous sinus. It requires immediate recognition and treatment.
Meningitis or Brain Abscess: Infections in the sinuses and mastoid can spread intracranially, leading to meningitis or brain abscess, both of which are medical emergencies.
Lemierre's Syndrome: A rare but serious condition characterized by a bacterial infection of the throat, leading to sepsis and thrombophlebitis of the internal jugular vein, which can be associated with mastoiditis and sinusitis in some cases.

Wegener's Granulomatosis (Granulomatosis with Polyangiitis): A rare autoimmune disorder that can cause sinusitis, mastoiditis, and other systemic symptoms.
Sarcoidosis: Although primarily known for affecting the lungs, sarcoidosis can also cause sinusitis and, less commonly, mastoiditis.
Histoplasmosis or Other Fungal Infections: Certain fungal infections can cause sinusitis and mastoiditis, especially in endemic areas or in immunocompromised patients.