Racing heart

Last May I started having racing heart I was put on a beta blocker, altho I suspected it was due to low b12 but nobody agreed with that.

My b12 was low for a long time but with the acceptable range (190) so doctor didnt act on it even tho I felt weak and unwell.

2 months ago she checked it again and b12 was 169 and Folate 18. My dr put me on 1000 mcg B12 daily. 2 months later b12 is 460 and folate is >20.

I read that high folate can cause heart racing when b12 levels begin to climb, because the folate is finally being correctly processed. None of my doctors are knowledgeable about any of this.

I need to know if anybody else was ever in this circumstance and how did it turn out for you?

Today I skipped the b12 and had no heart racing. This makes me think 1000mcg is too much daily and that my body is overwhelmed by the folate processing too quickly and at too large of volume.

What kind of doctor knows about vitamins and how they interact?

I don't even know if my theory is correct. Im not a doctor and Im just piecing together info I read online from medical sources but of course my interpretation is that of a lay person.

Thanks.