CHARLOTTE, N.C. -- Vikings rookie wide receiver Percy Harvin returned to practice Friday after missing most of two weeks and one game because of migraine headaches that left him unable to function. But it turns out this isn't the only issue with which Harvin has had to deal.

Andrea Kremer of NBC Sports reports that Harvin underwent an MRI last week that showed he has two bulging disks in his neck and is scheduled to go to the Mayo Clinic on Tuesday with a Vikings team doctor. Harvin told Kremer that after every game he has played since high school the back of his neck has been sore and swollen.

Harvin, who talked briefly about his issues with migraines on Friday but often refuses to discuss anything related to his health, told Kremer he arrived in Charlotte on Saturday with a lingering headache and drowsiness that he believes was caused by sitting in the pressurized airplane.

There have been reports that Harvin is expected to play in the Vikings' game against the Carolina Panthers on Sunday night but inactive lists aren't submitted until an hour-and-a-half before the 7:20 p.m. kickoff so his playing status won't be certain until Brad Childress submits his list of eight scratches.

Harvin, the odds on favorite to win NFL offensive rookie of the year honors, has dealt with migraines since he was 10 years old and they do run in his family. This latest round was so severe he not only was throwing up but had a loss of vision. NBC reported that Harvin saw two neurologists last week in addition to the team doctors. He has been put on medication and his personal plan the past two weeks was to get as much sleep as possible and stay hydrated.

Harvin admitted the migraines he experienced this time are similar to what he went through in 2007 at Florida, when he missed two games. That round was preceded by a sinus infection. This time he had the flu right before. "It was scary," Harvin told Kremer. "You want to do anything to stop it."

As for the time he has missed -- quarterback Brett Favre said he did not see Harvin once at Winter Park in the days leading up to the Vikings' victory over Cincinnati on Dec. 13 and last Wednesday Harvin had to go home early after becoming sick -- Harvin knows teammates might be wondering what is going on. Part of the issue is many players haven't known exactly what the situation with Harvin is because the team has been trying to get more answers.

"Guys could see how bloodshot my eyes were from crying and they saw me throwing up in meetings," Harvin said. "I think they know what was going on with me."

Harvin also told Kremer that he missed the Vikings rookie minicamp right after being the 22nd pick in the NFL draft last April and the NFL rookie symposium in late June because of migraines. In the first case, Harvin became sick during a layover in Atlanta and was taken to the hospital.

Harvin is second on the Vikings with 48 receptions for 681 yards and six touchdowns this season and has averaged 29 yards with two touchdowns on 34 kickoff returns. Last Sunday's game was the first he missed because of migraines. He believed to have experienced the headaches before games against the 49ers on Sept. 27, the Packers on Nov. 1 and the Bears on Nov. 29 but in each case was able to play.