Nelson, on the 60-day disabled list since Spring Training, underwent some shoulder cleanup in late March. He started rehabbing in Arizona but fell very ill in June. On June 25, the organization asked Nelson to return home.
Nelson barely left his bed for three weeks and rarely had any food.
"Every time I ate, I felt nauseated," he said. "I ate toast occasionally. One piece."
Nelson lost several pounds.
"My wife said I actually looked better losing all that weight," he said with a laugh.
Nelson saw doctors in two different states but no one could determine the sickness.
"I had it for 10 weeks and I just couldn't shake it," he said. "They haven't really pinpointed anything, but they ruled out everything else. In Arizona, they have something called Valley Fever, which is what they thought it was, but the people in Florida said it could have been that, but they are not 100 percent sure. I feel great now."
And that's a relief to the Royals. Nelson, who went 1-1 with a 4.43 ERA and nine saves as the Royals' rookie closer in 2006, is starting rehab again. On Tuesday, he embraced several KC personnel, including Tony Pena and Jimmy Gobble. Nelson will throw several bullpens in the next few days and join Triple-A Omaha when KC goes on the road next week.
"I feel good, and physically, I am over everything," he said. "My arm feels pretty good, still not at full strength."
Injury updates: Brandon Duckworth (oblique) made his first rehab appearance Monday night for Class A Wilmington. He tossed 2 1/3 shutout innings and allowed two hits against three strikeouts. The team is extending Duckworth so he can provide another option as a starter.
"Health-wise, there are no issues," Royals manager Buddy Bell said. "He is doing fine with the oblique."
John Thomson (back) will start a Minor League injury rehab session Tuesday with the Rookie League Arizona Royals.
Ryan Shealy continues to progress from his left hamstring injury with Triple-A Omaha. Shealy, who has hit very well in the past week, is batting .302 with five homers and 15 RBIs in his rehab work. Shealy's rehab assignment is expected to end Wednesday and he can either rejoin the team or be optioned to Triple-A.
"We talked about it briefly," Bell said. "We are going to talk about it more [Tuesday] and [Wednesday]."
Jorge De La Rosa (left elbow strain) had a MRI on Monday, but it didn't show any further damage. Bell expects De La Rosa to miss two weeks and make at least one rehab start.
Davies at Kauffman: Kyle Davies, acquired at the trade deadline from the Braves for Octavio Dotel, made his first appearance in Kansas City since he played here as a youngster.
Davies, who worked just three innings and allowed five runs (including Alex Rodriguez's 500th career homer) in a loss to the Yankees, is happy to play for KC. Davies had struggled with the Braves, posting a 14-20 career record.
"New eyes, fresh voices," he said. "I needed a change of scenery. You can kind of start over and stop pressing so much and just play the game."
Davies said he needs to improve his four-seam command and consistently repeat his delivery to improve as a pitcher.
"I have enough experience at the Major League level, and now it is time to start putting some of it together," he said. "The biggest thing, I think for me, is to consistently locate my fastball. If I do that, then everything else is good enough. I can throw curveballs for strikes and I can throw changeups for strikes, but it all boils down to locating your fastball. The most success I have had is when I have been able to locate that."
Royals hold charity function: Royals Charities will host the third annual Royals Charities Back to School Drive to benefit Our Lady of Guadalupe Elementary School on Wednesday at Kauffman Stadium. Royals Wives and Royals Charities will collect school supplies at Gate B at Kauffman Stadium from 5-7 p.m. CT. Additional drop-off sites will include Gates A, C and D.
O'Neil seat: Linda Anthony from Kansas City, Mo., was sitting in Buck O'Neil's seat for Tuesday's game. Anthony has spent several years with Adopt a Pet and provided her residence as a foster home for animals until permanent homes could be found. Many animals, instead of being euthanized, found loving homes.
Royals rundown: Triple-A Omaha lost, 6-5, to Tucson on Monday. Tyler Lumsden allowed five runs (three earned) in three innings and took the loss. Mike Aviles and Craig Brazell each had two hits and one RBI for the Royals. ... Double-A Wichita lost, 4-3, to Arkansas. D.J. Mattox allowed two runs on two hits in six innings, while Jorge Padilla (.357 average) and Kila Kaaihue each had two hits and a run scored. ... Class A Wilmington won, 4-2, over Winston-Salem. Julio Pimental (9-4, 2.76) worked 4 2/3 relief innings for the win. ... Class A Burlington won, 6-5, over South Bend. Derrick Robinson collected two hits, two RBIs and his 27th stolen base of the season. Joe Dickerson also had two hits, two RBIs and two stolen bases. He has 24 swipes this year.
Advanced Rookie League Idaho Falls lost to Ogden, 5-4. Adrian Ortiz, the Royals' No. 5 pick in the 2007 Draft (.322 average, nine stolen bases) collected three hits, a run scored and an RBI. ... Rookie League Burlington lost, 11-7, to Bluefield. Patrick Norris had two hits, two runs and two RBIs in the loss. ... Arizona lost, 2-1, to the Arizona Mariners. Peter Hodge Nielsen, the Royals' fourth-round pick in the 2007 Draft, pitched four innings of one-run ball and lowered his ERA to 3.16.
Coming up: Odalis Perez (6-10, 5.79) will face reigning Cy Young Award winner Johan Santana (11-9, 2.98). First pitch Wednesday is scheduled for 7:10 p.m. CT.
Conor Nicholl is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.