Feeling Dizzy and Weak: Seeking Advice

It’s been a while I’ve been on here but I just hope everyone’s well. I’ve been doing OK I guess I’ve been dizzy for a while now they’re saying I’m going through some tests right now but they did bloodwork. They found my B12 is very low so I’m gonna gummy B12, but I guess the doctor wrote the script but they wouldn’t do it at the pharmacy. I don’t know if it’s any difference in the B12 that they want me to get in the pharmacy or on the shelf Always someone will tell me they say it could be vertigo I mean I get dizzy pretty good and my stomach bothers me but I guess that’s part of the vertical. The problem is I’m still really weak tired and they ran test and everything and they said everything’s good, does anyone have any pointers? Maybe they can give me what could it be? Thank you.