By HOWARD FENDRICH AP Tennis Writer HOURS after losing his most recent match, Mardy Fish woke up in the middle of the night feeling ill and immediately went to be checked by a doctor. He saw another doctor the next day, too, and the diagnosis was fatigue. Told he needed to rest, and citing what the US Tennis Association called a "minor health scare," the No. 9-ranked Fish pulled out of this week's Davis Cup quarterfinal between the United States and France in Monte Carlo. "We don't want to get exactly into what the symptoms were. He didn't feel normal. He said, 'Hey, something's wrong here.' He was concerned about it," Fish's agent, John Tobias, said in a telephone interview Monday. "His body got out of whack, caused by a number of different variables ... (but) they ruled out any potential long-term issues." Late on Monday, Fish wrote on his Twitter page: "Thanks all for the nice messages. Resting comfortably with family. Hope to be back out there soon." Fish, the highest-ranked American, lost 6-1, 6-3 on Thursday to Juan Monaco in the quarterfinals of the Sony Ericsson Open at Key Biscayne, Florida. The 30-year-old Fish appeared to be fine physically and said afterward he would have preferred more taxing conditions for the afternoon match. "It was like the weather was almost too good," said Fish, who lost about 30 pounds after having knee surgery in September 2009 and prides himself on his fitness. "It wasn't that humid and it was a nice, comfortable temperature. So I was expecting it to be hotter. I wanted it to be kind of a Florida day. It was an LA day, I think." Fish also said he was encouraged by his play in the tournament after a disappointing start to the year. It was the first time he has won consecutive matches at a tournament in 2012. Fish's biggest victory this year came in February in the first round of Davis Cup, when he rallied to edge Stanislas Wawrinka 9-7 in the fifth set, helping the US beat Switzerland. From Switzerland, Fish went home to California, before traveling to Marseille, then Dubai, then home again, before tournaments at Indian Wells and Key Biscayne. "Just a crazy amount of travel, and the time-zone changes, kind of wears you out after a while," Tobias said. On Thursday night in Miami, Fish didn't feel well and saw a doctor. His parents live a few hours away in Florida, and he went to see the family doctor on Friday. After spending the weekend at his parents' home, Fish was going to fly to his place in California on Monday, Tobias said. The agent said Fish will consider making changes to his schedule now, but he could still play next week at Houston. And Fish intends to compete on the European clay-court circuit at Rome and Madrid before the next Grand Slam tournament, the French Open, which begins May 27. Tobias said that "absolutely, 100 percent" Fish will play at Roland Garros. "We're just going to scale him back a little bit and make sure that he arrives at a tournament well-rested and ready to compete," Tobias said. "His commitment to Davis Cup is like none other. It's absolutely killing him to miss it this time." Ryan Harrison replaced Fish on the US roster against France, which will be missing 14th-ranked Gael Monfils because of an abdominal injury.