I am sorry that your father had to suffer an attack of fits
when all seemed fine.
It is not a rule that a person with normal CT scan
and EEG and completed treatment does not suffer a fresh attack of fits again in his life.
I hope you are getting my point.
There could have been a trigger for this new fit to occur recently.
The medicine is not to be taken for lifetime. However, it is important to take the medicines for a minimum of 3 years after the last attack of fits.
I hope to have given you some insight as to what is happening to your father.
I wish your dad a very good health and speedy recovery.