I'm really worried about my mom. Her heartbeat's been acting up and she's feeling a heavy sensation around her chest. About a month ago, her hemoglobin was really low at 6, and the doctor suggested 7 cycles of iron injections. She's already done five of those. The last four times, it took about 2 to 2.5 hours to finish each cycle, but the nurse did the fifth round in just an hour. Also, they usually fixed the cannula on the back of her hand, but during this last session, they put it on her wrist and told her to hold it. Do you think these changes could be why she's feeling chest heaviness and her heartbeat's speeding up? Can the quick iron injection cause these symptoms?