Since your doctor had prescribed carbamazepine (Mazetol) several years ago, he had diagnosed epilepsy as the cause of your symptoms. The calcified lesions seen on the new scans are evidence of long-standing abnormalities. There must have been some infection or parasitic infestation in the brain years ago - perhaps when you had your epilepsy - which your immune system and nature have overcome. The dead tissue in the brain has since been the site of calcium deposition. This is common in many parts of the body.
These are healed lesions and need no surgery. They are unlikely to develop further. They can, however, cause fits, as in your case. This is why your doctor has prescribed, once again, the same drug - carbamazepine (Tegrital) - to control fits.
There is no cause for concern. As long as you continue taking the medicine under the supervision of your doctor, you should do well.