"I have a bad case of sinusitis, bronchitis too," said Gasol after practice Monday. "Right now we're really short-handed and we need everything we can get out there. I'm going to do my best."
The team has dropped five straight games to fall to 13-18 and 13th place in the Western Conference.
The Lakers' forward-center may have confused fans by sitting out a visit to the Golden State Warriors on Dec. 21, returning for games against the Phoenix Suns and Miami Heat, but then sitting the last two against the Utah Jazz and Philadelphia 76ers.
Gasol said his condition worsened after playing against the Suns and Heat.
"I'm really stuffed up. All my cavities are infected," he said. "I just get very exhausted and winded when I get my cardio up."
Gasol dealt with an upper-respiratory infection earlier in the season. The relapse has been severe. He saw an ear, nose and throat specialist last week.
"The doctor said that I never really got over it. I just got better for a month and it hit me badly again," he said. "I'm going to be on antibiotics for a while."
With the Lakers losing their last five games, Gasol will return to the court despite his current condition.
"I won't be [healthy] for weeks," said Gasol. "I'm going to play tomorrow."
"My teammates want me to be on the floor," he continued. "They count on me. I'm just going to do my best to deliver and be a support for my teammates. ... My goal and our goal is to win the next three — no matter how, no matter what."
On the season, Gasol is averaging 14.7 points and 9.4 rebounds through 28 appearances. He's recently faced media criticism for sitting out, when the Lakers so clearly needed him on the floor.
"I played through when I first got the respiratory issue early in the season and I was getting killed by not performing," he said. "When you try to play through stuff, you still don't get any credit.
"I'm just trying to do what's best for myself and the team in this case," he continued.
The Lakers are still waiting for the results on Xavier Henry's MRI after he strained his right knee Sunday night in the loss to Philadelphia.