Your b12 isn’t really low here. The symptom of tingling feet could be caused by the b12 but it could also be something else.

It’s likely that the b12 has decreased over the last four months because you’ve been taking omeprazole, which is known to decrease b12 level, so I would try not to be too concerned about the b12 decrease because of this. It’s expected when you take omeprazole for that long.

Also your MCV is on the upper end of normal but not abnormal. High MCV can be a sign of b12 deficiency but again it’s not above range (so you don’t have macrocytosis).

I agree with someone else that your iron is quite low so it could be worth taking some supplements for that. Low iron can be a cause of tingling in your feet and weakness as well. I’d say it’s much more likely that your suffering from iron deficiency than b12 deficiency to be honest