She hinted at being injured but refused to elaborate.
"I am not here to make excuses. Everyone has setbacks. I am not going to put anything in print yet," she told reporters.
Campbell is no longer the star of the Australian swimming show - that mantle belongs to newcomers at their first Olympics.
Kyle Chalmers helped the men's 4x100m medley relayers to bronze on Saturday night, after winning gold in the 100m freestyle.
Emma McKeon is Australia's most successful swimmer in Rio, winning one gold, two silver and a bronze.
Throw Mack Horton in the mix too. Not only did he win the 400m freestyle gold, he also sparked a global debate on the presence of past drug cheats at the Rio pool.
"It's good to have kicked it off," Horton said after finishing fifth in Saturday night's 1500m freestyle final.
"I kind of followed it throughout the week but I didn't let myself get caught up with it."
Horton and Chalmers were Australian swimming's individual gold medallists in Rio.
Other individual medals went to Mitch Larkin (silver, 200m backstroke), Madeline Groves (silver, 200m butterfly) and McKeon (bronze, 200m freestyle).
Their success stories accompanied unexpected flops.
Cameron McEvoy arrived as the fastest male 100m freestyler in the world but admitted to stage fright after his seventh placing in the final.
His blushes were lessened by two relay bronze medals.
Emma Seebohm lobbed as reigning 100m and 200m backstroke world champion. She left with only a medley silver.
Her boyfriend Larkin entered as reigning 100m and 200m world champion. He left with one silver.
And Bronte Campbell came as reigning 100m freestyle world champion. She left with just a freestyle relay gold.
And, like her older sibling, Bronte hinted at a shoulder injury.
"It's not an excuse. I will just say I wasn't best on the day," she said after placing seventh in Saturday night's 50m freestyle final.
- AAP
