I also had the exact same reaction. I had a complete physical in April 2021, before changing jobs and all blood work was in normal range. I had the 1st dose of the Pfizer vaccine in August and the 2nd on Sept 4. I started noticing fatigue, as it progressed by heart rate was elevated. I went to urgent care and they did an ekg, chest x-ray and blood work. My hemoglobin dropped to 6.8. They also suspected an internal bleed. I went to the emergency room and was given 2 pints of blood. I have never has an issue with anemia before. Nothing in my normal routine has changed. I can only assume it is from the vaccine as well.

I had my first vaccination in March 2021 and in less than one week I tested positive for Covid. While I was ill, my blood pressure dropped dramatically (bordering on dangerously low) and I could not stand up without feeling as if I would pass out. It wasn't until approximately two months later that I had my iron checked and discovered that I was suffering from low iron and low ferritin. I had just assumed that the severe drop in my BP and ongoing shortness of breath were the result of Covid but now I wonder whether all of this was actually caused by the iron depletion as a side effect of the vaccination instead. The many accounts from people who do not indicate that they had Covid seem to point to the vaccination. As mentioned, I had one shot (Moderna) followed by Covid and an infusion of monoclonal antibodies (Regeneron). I did not get my second vaccination and will not get a booster. I believe, and evidence seems to indicate, that natural antibodies are at the very least, as good as the vaccine, are longer-lasting and more effective. And all these months later I am still waiting for my iron/ferritin levels to be where they belong.