Cerebral stroke (recurred): Given the patient's history of a previous stroke, recurrence is a significant consideration, especially if risk factors such as hypertension, diabetes, or atrial fibrillation are not well-managed. The CNS manifestations could be indicative of a new stroke, which would be a direct and likely cause of the symptoms.

Amoebic brain abscess: Although rare, the patient's travel to Mexico increases the risk of exposure to amoebas like Naegleria fowleri or Entamoeba histolytica, which can cause brain abscesses. The CNS manifestations and the CT findings could be consistent with an amoebic brain abscess, especially if the patient had exposure to contaminated water.
Other infectious causes: Considering the travel history, other infectious causes such as neurocysticercosis (common in Mexico) or toxoplasmosis could also present with CNS manifestations and abnormal CT findings.

Neurocysticercosis: This is a critical diagnosis not to miss, given the patient's travel to Mexico, where neurocysticercosis is more common. It can cause a variety of CNS symptoms and has a range of appearances on CT scans, including cystic lesions.
Meningitis or encephalitis: These conditions can present with CNS manifestations and require urgent diagnosis and treatment to prevent serious complications or death.

Hydatid cyst in the brain: Although hydatid disease is rare in Mexico, it's not impossible, especially if the patient had exposure to the parasite (Echinococcus granulosus) through travel to endemic areas or contact with infected animals. Brain involvement is rare but can occur, presenting with cystic lesions on imaging.
Other rare parasitic infections: Depending on the specific travel history and exposures, other rare parasitic infections could be considered, though they would be less likely without additional specific risk factors.