Cavernous Malformation with Residual or Recurrent Bleeding: The patient's history of a small bleed and the presence of a cavernous malformation with a developmental venous anomaly (DVA) make this a likely cause of symptoms. The improvement over time could be due to the body's compensation mechanisms or partial resolution of the bleed, with flares possibly indicating minor recurrent bleeding or changes in the malformation.

Seizure Activity: Given the location and nature of cavernous malformations, seizure activity could be a cause of symptoms, especially if the malformation is located near eloquent brain areas. The improvement and flares could be related to varying seizure frequencies or intensities.
Mass Effect or Edema: The cavernous malformation and associated DVA could cause mass effect or edema, leading to symptoms. The improvement could be due to reduction in edema or adjustment of surrounding brain tissue, with flares indicating transient increases in edema or mass effect.

Infectious Process (e.g., Brain Abscess): Although less likely, an infectious process could present similarly, especially if the cavernous malformation has bled, creating a potential nidus for infection. Missing this diagnosis could be catastrophic.
Malignant Transformation: Rarely, a cavernous malformation could be associated with or undergo malignant transformation. This would be a critical diagnosis not to miss due to its significant implications for treatment and prognosis.

Venous Thrombosis: Thrombosis within the DVA could cause symptoms, either through mass effect, venous infarction, or by affecting the function of the cavernous malformation. This would be a rare but possible cause of the patient's symptoms.
Neurodegenerative Disease: In some cases, neurodegenerative diseases could present with focal symptoms that might mimic those caused by a cavernous malformation, especially if there are associated vascular changes. However, this would be a less direct cause and might not fully explain the imaging findings.