Smelly sputum with 39.5 degrees c. & chest x-ray showing left basal cavitary lesion. what does this mean? what is this diagnosis?

Different causes: With infection in lungs cavitary lesions can be seen with granulomatous disease such as TB ,fungi, or coccidiodomycosis (valley fever). Staph infection and other bacteria can have cavitation. Metastases and neoplasms also can have necrosis or cavitation.

See below: You likely have a lung abscess. You should see your physician right away. You need clindamycin at the very least. You will likely need a bronchoscopy as well to help determine if this in fact infectious, vs a malignancy.