Does this sound like an allergic reaction??

So I’m anemic and have been taking iron tablets for the past 2 weeks, I have suddenly got really bad chest pains and having trouble breathing I feel like I’m being choked and my heart being squeezed.

I went to the hospital and did all tests they came back fine I had X-ray it came back fine, they are doing a test again tomorrow but she said it will likely come back fine because they already did one they just want to do another one for 24 hours.

Is it possible that I’m having an allergic reaction to the iron tablets ferrous sulfate? Or would I have experienced symptoms sooner.