(CBS) — Published reports say former teacher’s union Karen Lewis has a cancerous brain tumor after first complaining about a severe headache.

CBS 2’s Marissa Bailey reports on whether headache sufferers should be concerned about something more serious.

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Laura O’Brien had a baseball-sized tumor removed from her brain, just two weeks ago. She had a very bad headache, what she calls “the headache of my life.”

Not even the strongest medication took away the pain, and after an MRI doctors determined it was a benign tumor.

Rush University Medical Center’s chief neurosurgeon says there are some warning signs to keep in mind, when trying to differentiate between a run-of-the-mill headache and something worse.

“The headaches that we worry about in medicine are the headaches that are really severe, that come that won’t go away, that wake you up at night, associated with nausea, vomiting or some sort of neurologic deficit,” Dr. Richard Byrne.

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O’Brien is doing well.

“I have a new lease on life, and I am just filled with gratitude,” she says.

Despite all this, doctors say two-thirds of headaches are just that: headaches. If you have any doubts, though, you are encouraged to consult your physician.

The Chicago Teachers Union on Tuesday tweeted a message, saying, “Karen appreciates the love and support. Please send your cards, flowers, letters, get well greetings to CTU HQ.”

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