New York ? Ailing Yankees first baseman Jason Giambi was diagnosed with parasites and out of the starting lineup Tuesday night when New York played Boston.

When asked specifically what the doctor told him, Giambi said he didn’t remember.

“I don’t have a Ph.D., and I’m not world-renowned,” Giambi said.

The former AL MVP said he had been feeling exhausted for about three weeks. He began taking a new set of antibiotics Tuesday and said a doctor told him he should feel better within a couple of days.

“There should be no reason for being this exhausted,” Giambi said. “I’m 33, not 50.”

Giambi has one hit in his last 14 at-bats and is in a 13-for-65 rut.

He hasn’t homered since hitting his 11th of the season June 20, and his average has dropped from .271 on June 7 to .237.

“This sort of explains it to be more than a slump,” Yankees manager Joe Torre said.

Giambi said he wasn’t surprised Yankees owner George Steinbrenner recently had criticized him a bit.

“In some cases, he was right,” Giambi said. “I wasn’t feeling real good, and I was hurting the team.”

“It kind of makes you understand why you’re getting jammed by guys throwing 88 miles an hour.”