First thing that came to mind was B12. Good that you're getting it checked. Folic acid can mask a B12 deficiency. B12 serum testing alone may not be adequate to uncover a B12 deficiency. If you suspect B12 is an issue and B12 serum comes back in the normal range, then more conclusive testing would be warranted.

You may want to consider adding b12 followed by a B complex a week or two after.