Armond Armstead awaiting test results

USC senior defensive end Armond Armstead spent five days at the USC University Hospital earlier this month, but little information was provided at the time about the "unspecified medical condition" that USC announced as the reason for his hospitalization.

Tuesday, he provided some context as to what exactly happened that led him to the hospital and what kept him there, and what's continuing to keep him out of spring practice.

"I was having some chest pains, so that's what caused me to go initially," Armstead said after Tuesday's practice, during which he stood on the sidelines in uniform but did not participate. "I'd been sick for a couple weeks -- it was an ongoing thing. I was coordinating with the trainers and the staff and then going to see the doctors, trying to figure out what was going on."

Armstead, 20, is expected to start at defensive end for the Trojans in 2011 after starting there for much of the last two seasons. But he's being held out of spring practice until he and the USC athletic department hear back from the doctors on the case.

The earliest any word will come on whether or not he'll be cleared to play, Armstead said, is April 1, when he's scheduled for an appointment with the doctors who worked with him earlier this month.

"We're still getting stuff back in," USC coach Lane Kiffin said Tuesday. "Some tests have not come back, so we're holding him out in the meantime."

Armstead said much of the time he spent in the hospital was spent on blood testing. Once he was released from the hospital on March 9, he said, he felt back to normal.

"I feel fine now, that's the thing," Armstead said. "As soon as I got out of the hospital I was just at home chilling with my family and I felt great. I wanted to move the appointment up with the doctors to see if I could get the results sooner but the tests haven't come back yet."

He has been fairly injury-prone at USC, but he stressed that the chest pains had nothing to do with any football-related injuries and were instead caused by sickness. Armstead, who chose not to declare early for the NFL draft, also said he was doing his best to take a positive approach to what could be a serious long-term issue.

"Yeah, of course, because it's chest-related, but I'm just being very careful and hoping for the best," Armstead said. "You can't say what it is until the doctors tell you what's going on."

Pedro Moura covers USC for ESPNLosAngeles.com.