CHARLOTTE, N.C. - Upon meeting Minnesota Vikings wide receiver/kick returner Percy Harvin for the first time, one can’t help but be drawn to his charisma, manners (“yes ma’am, no ma’am”) and big smile. Hard to believe that only days before he was literally crying himself to sleep.

So says Harvin, whose debilitating migraine kept him out of practice for nearly two weeks and forced him to miss last week’s game against Cincinnati but will not keep him out Sunday against Carolina. The 21-year-old, who has suffered from migraines since he was 10 years old, said this was the worst one he’d ever had.

“It was scary,” said Harvin, who leads the NFC with 1,780 combined yards heading into Week 15. “You want to do anything to stop it.” Harvin told me he arrived in Charlotte with a lingering headache and drowsiness, he believes, from the pressurized airplane.

This week Harvin also got the surprise news that an MRI showed two bulging discs in his neck. And he told me that after every game he’s played in since high school, the back of his neck is sore and swollen, all factors that require more investigation. Harvin said he is scheduled to go to the Mayo Clinic on Tuesday with a Vikings team doctor.

Harvin said his mother suffered from migraines as well, and he’s been told they can be genetic. Typical triggers for his migraines have been spending too much time in the sun and eating chocolate, he said. However, this episode was preceded by a bout with the flu. Harvin said it was reminiscent of his previous most serious attack in 2007, which was triggered by a sinus infection and caused him to miss two games at Florida.

This time around, Harvin’s symptoms included loss of vision and throwing up. He saw two neurologists this week in addition to the team doctors, and he’s currently on medication. During the past two weeks, his personal prescription was to get as much sleep as possible and stay hydrated.

One NFL team doctor told me that there is no known correlation between concussions and migraines, yet just as some skepticism exists in NFL locker rooms about the seriousness of head injuries, Harvin said some teammates might look askance at him for missing time with a migraine. “Guys could see how blood shot my eyes were from crying and they saw me throwing up in meetings,” he said. “I think they know what was going on with me.”

Few should question Harvin’s toughness. Vikings coach Brad Childress certainly doesn’t. Childress recounted the story of the rookie’s first preseason game when he wanted to return kicks despite an AC (shoulder) sprain. Childress said Harvin begged the coach to play, asserting that once he caught the ball no one would catch him to hurt him. Childress said they had to protect him from himself and kept him out of the game.

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Harvin, who entered the league in the substance abuse program after testing positive for marijuana at the Scouting Combine in February, raised some eyebrows when he missed the mandatory NFL Rookie Symposium in late June as well as a Vikings rookie minicamp after the draft. Harvin told me that both absences were due to migraines.

Harvin is the leading candidate for Offensive Rookie of the Year and would be only the second wide receiver since 1998 to win the award (the other was Anquan Boldin in 2003). But first he must overcome an obstacle more dangerous than any defense — the one that throbs in his own head.

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