Brian Vickers out at least 3 months

FONTANA, Calif. -- Brian Vickers will miss at least three months while he is on blood thinners for clots that developed in his lungs Thursday.

The Michael Waltrip Racing driver said Sunday at Auto Club Speedway that he hopes that he will be able to go racing again. As long as he is on blood thinners, he cannot race because of the danger of bleeding out if he is involved in an accident.

The 31-year-old Vickers, forced to sit out for the fourth time in his career because of treatment for blood clots, has three wins in 318 career Cup starts and is in the final year of his contract at MWR.

He could miss longer than three months, and he would be forced to retire if doctors determine it is too risky for him to go off blood thinners.

"Am I worried? Of course," Vickers said. "Have I given up hope? No."

Vickers first experienced blood clots in his lungs and legs in 2010, when he missed the final 26 races of the season, initially for going on blood thinners and then for heart surgery in July 2010 to patch a hole in his heart.

He then missed the final five weeks of the 2013 season when he developed a blood clot in his leg. In December, his body began rejecting the patch inserted in 2010 and he had surgery to replace the patch. He missed the first two weeks of the season to allow his sternum to heal enough in case he got in a crash.

Vickers returned for the last two races before experiencing the small blood clots Thursday.

"Through those three months [I'll be out], I'll just try to figure out what makes sense with my doctors to see if I can come back off of them and go racing, if there is some kind of plan that works," Vickers said. "If not, then that's that.

"But we're so far away from crossing that bridge at this point, I can't really say. That [retirement] question has crossed my mind about a thousand times in the last 24 to 48 hours but the funny thing is I've been told now three times I would never race again and I've raced the last two weeks. I'll never give up. Listen, if it comes to that, then I'll move on to the next thing in life."

MWR development driver Brett Moffitt is in the team's No. 55 car Sunday at Auto Club Speedway, and no decision has been made for beyond this weekend.

The team has not ruled out any options, including the possibility of releasing Vickers and putting Moffitt or another driver in the car full time regardless of when Vickers is able to return.

"Absolutely zero has been decided moving forward at this point because it has all been focused on doing the right thing this weekend and understanding a little bit more about what Brian's situation is," MWR executive vice president Ty Norris told ESPN.com on Sunday morning. "In the last 48 hours, there have been a million thoughts that have crossed everyone's minds. ... When we gather all the facts, we'll sit down as businessmen and decide what we're going to do."

Vickers said he hoped MWR would allow him to return to the car if he can get off the blood thinners. Once he is off blood thinners for a couple of days, he can race.

"I love racing more than any other activity that I do," Vickers said. "I don't love it more than my wife. Or my family. Or my friends. It's not who I am. It's something that I do. It's something I love doing. But there's more to life than just this."

Treated at the UCLA Medical Center in Santa Monica this week, Vickers said he has not been able to sit down with his own doctors to determine what caused the most recent clots. His 2010 clots were caused for him being immobilized after a wreck at Talladega and then being on a plane for several hours. His 2013 clots were caused by a brace he was in after a wreck at Bristol.

He began experiencing pain in his chest Thursday and knew what likely caused the pain.

"I went to the hotel to check in because I was still trying to convince myself it was something else," Vickers said. "I sit there for a few minutes and kind of paced the room with [wife] Sarah and was trying to figure out if I could turn my chest pain into something that it wasn't. ... I told her that if I go to the hospital, I'm not racing this weekend.

"She was very sweet and encouraging. She was like, 'You don't know that yet. Let's just go get it checked out.' I was like, 'Yeah. I know.' "

Vickers has gone back on Xarelto, a drug made by Janssen Pharmaceutical that is sponsoring Vickers' car this weekend. A Janssen executive said Saturday that it would continue to support Vickers, who could have trouble landing sponsorship in the future because of the possibility he could again be sidelined for blood clots. The company is continuing to run commercials with Vickers, who is battling a reaction by some on social media that he was still taking the drug when he developed the most recent clots.

"Because he is such a great ambassador for the sport, for people who are at risk for clots, we are very excited to be working with him and will continue to work with him," said Janssen marketing director Michael Moye. "If he does race or if he doesn't race, we are going to partner with him again."