Hi Andrew, it's great that the B12 has helped you, take it on a empty stomach for best absorbtion, i take mine at night just before retiring for bed, I would keep taking it indefinitely, you must have been very low in the vitamin , you can't have to much b12 in your system the more the better.
A good quality multi B would be good to take as well in the morning.

best of luck to you.
Brian