My crush coughed up blood but she doesn't care, should I be worried?

My crush coughed up blood but none of her friends, including her, seems to have cared about it. Her first reaction was about her clothes being stained, of course I panicked. I told her she should see a doctor but she said she was fine, she had worse. She said "this is nothing, I coughed up more blood yesterday". One of her friends also ensured me that is was "fine" saying that it was probably just stress. Does stress even cause someone to cough up blood? It she really just "fine"? Help?
My crush coughed up blood but she doesn't care, should I be worried?
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