ST. LOUIS -- Having regained strength after weaning himself off medication that was causing adverse side effects, Jhonny Peralta expects to report to the Cardinals' complex in Florida next week to return to the field in rehab games. That could position him to be activated from the disabled list when the Cardinals are in Miami for a series from May 8-10.

Peralta resumed taking swings in the batting cage on Friday and would have been on the field for pregame work before Saturday's game had weather not washed it out. His disabled-list stint is backdated to April 16, but it's been only recently that Peralta felt a change in energy level.

What started as a seemingly innocuous upper respiratory illness in the final days of Spring Training turned into a much more serious medical issue when the prescribed medicine started making Peralta worse. Concerned about how weak he looked following a strong showing in spring, the Cardinals ran blood work on the third baseman in mid-April. That revealed other problems, including an elevated liver enzyme count.

"They gave me some medicine, and instead of feeling better, I felt worse," Peralta said. "I felt weak in the field. Kind of dizzy a little bit. No energy in the field. Getting tired easily. Nothing felt right. I knew something was bothering me."

It did offer an explanation as to why someone who was showcasing power and quickness all spring looked sluggish when the regular season started. In eight games, Peralta, who was the team's Opening Day third baseman, went 3-for-25 with no extra-base hits and nine strikeouts.

Manager Mike Matheny pushed the medical team to do a deeper dive into Peralta's health situation to try and determine the underlying issue behind Peralta's legthargic look.

"You get concerned about guys when something doesn't look right," Matheny said. "Jhonny was really good about being honest about how he was feeling. ... I think deep down, once we started talking about [it], he realized something didn't feel right."

Peralta continues to meet with the Cardinals' doctor daily and has had blood drawn regularly to ensure that he's trending in a better direction now that the medication is out of his system. Next, he'll have to prove that, when healthy, he can still produce.

With Jedd Gyorko emerging as one of the club's best players in April, it's not certain where Peralta will fit back in.

"More than anything, I know my body," Peralta said. "And I knew I didn't feel right in the field. I know what I can do, but at the same time, when your body doesn't feel right, there's nothing I can do in the field. I don't want to say 100 percent that's why [I was performing poorly]. But I didn't feel right."

Jenifer Langosch has covered the Cardinals for MLB.com since 2012, and previously covered the Pirates from 2007-11. Follow her on Twitter, like her Facebook page and listen to her podcast.