Brandon Moss “feels great” 18 days after undergoing an emergency appendectomy. The Red Sox rookie played three games at extended spring training and will now play for Pawtucket.

The Providence Journal / Bob Breidenbach

BOSTON — Brandon Moss had his uniform on, a smile on his face and a bat in his hand as he was walking around the Red Sox’ clubhouse yesterday afternoon. Eighteen days after undergoing an emergency appendectomy, the rookie outfielder/first baseman was rarin’ to get back on the field.

“I feel great,” Moss said as he prepared to meet with a doctor and get in some on-field work.

Moss has played three games in Florida, and he will play for Pawtucket tonight when the PawSox begin an eight-game homestand by hosting Rochester. Moss is not sure when he will return to Boston. For now, the uncertainty of where he will play is not nearly as important as simply being able to play.

“I don’t know what they’re going to do,” he said. “I might stay there (in Pawtucket). I don’t even know. Whatever happens happens. I’m just glad to be able to play again.”

Moss told an interesting story of what he has been through. It started three weeks ago today when he had stomach problems.

“I had a stomachache for about two days. I thought that I had food poisoning at first. I was sick like I had food poisoning,” he said. “Then, the next night, it was like a normal stomachache, like you would have after you had food poisoning.”

That second day was May 2. That was the night he started in right field, threw out a runner at the plate and hit a home run into the bleachers to help the Sox beat Tampa Bay.

The next day, a Saturday, he still was not feeling well.

“It had all moved over to one side. So I just figured maybe I had some gas from it,” he said. “I was down in the training room asking for some gas medicine. They said, ‘If it’s been that long, let’s get it looked at.’ The doctors looked at it, and three hours later I was out of surgery.”

It was a whirlwind.

“They said, ‘It (his appendix) is going to have to come out.’ I’m like, goodness gracious, you’ve got to be kidding me.”

Everything happened so quickly that he was out of surgery and in a recovery room before the Sox’ game that night was over. The game was on television, but he was so out of it that he doesn’t remember much.

The next morning, he was out of the hospital. He was told it likely would be three to five weeks before he would be playing baseball again. The first few days, he did not dispute that.

“It didn’t feel great to get up and walk around. They go through the abs. It’s really tight, it’s really sore. But a couple days later I was walking around, doing everything fine, running on the treadmill. I was a little surprised that I was able to do all that so quick, but I was definitely happy because it was better than sitting in the hospital,” he said. “I don’t like hospitals very much.

“They told me the more I did, with moderation, the better it would get and the quicker it would get better,” he said. “Even though it hurt, I kept doing it and it got better a lot faster. The progression was really good.”

With the help of his wife — “she gave me a lot of ice cream and cookies the first couple days,” he said — he did not lose any weight. By last weekend, he was in Florida working with the rookies and others in extended spring training at the Red Sox’ minor-league complex in Fort Myers.

He played in three games, two at first base and one in the outfield, and had 15 at-bats. He was pronounced ready to go, with good reason. In the three games, he went 8-for-13 with two walks, a double, a triple, a home run and five RBI.

“He’s made some kind of recovery,” said Sox manager Terry Francona.

pkenyon@projo.com