Weeks after waking up in the middle of the night feeling ill, Mardy Fish is not certain when he'll return to the tennis tour and says he could miss the French Open.
The highest-ranked American is also still trying to figure out exactly why he felt the way he did.
"I'm doing OK. We're doing lots of tests to try to figure out what's going on and what went wrong," Fish said Tuesday in a telephone interview from California with The Associated Press. "It's sort of unclear as to how or why it happened yet, but we're trying to figure it out. It's not something I'm super comfortable talking about. It certainly was a scare."
Hours after losing a match at Key Biscayne, Fla., on March 29, the No. 9-ranked Fish went to be checked by a doctor, then saw another doctor the next day. The diagnosis was fatigue, and he was ordered to take some time off. He pulled out of the U.S. Davis Cup team's quarterfinal against France the following week.
"That was really devastating and disappointing to not be able to go there," Fish said. "If you know me, you know that it had to be something pretty significant."
Fish then returned briefly, losing his opening match at a tournament in Houston on April 12.
As for his upcoming schedule, Fish said he'd like to take part in the European clay-court circuit by entering the events at Madrid, starting May 6, and at Rome, starting May 13.
But he doesn't know whether he'll be able to participate there -- or if he'll make it to the year's second Grand Slam tournament, the French Open, which begins May 27.
"I'm not 100 percent sure whether I'll be back for that," Fish acknowledged, "but that's the goal."
One part of the calendar Fish has made a decision about is in late July and early August: He will skip the London Olympics and plans to play instead at the Citi Open, a hard-court tournament in Washington formerly known as the Legg Mason Tennis Classic.
Fish won a silver medal in singles at the 2004 Athens Games.
"I definitely thought about going -- the prospect of playing the Olympics at Wimbledon on a grass court, a surface that suits me very well. I have some great memories from the Olympics. ... I also have some tough memories from it as well, where I was so close to winning a gold medal," Fish said. "That loss hurt as much or more than any loss I've ever had in my career. So I stayed away in 2008 for Beijing and I'm going to stay away this time."
The 30-year-old Fish has a 7-6 record in 2012.
Last season, he reached a career-best ranking of No. 7 and took part in the season-ending tour championships for the first time. That meant his season was longer than usual, which might have worn him out.
"It was a good problem to have, but I kind of ran into not having a break of more than four weeks in a row for 12 months. ... So I needed a break -- and I'm taking it now," Fish said.
"I'm taking some time now to kind of relax," he added, "and try to keep my mind off tennis a little bit."