"Right after judging, I turned my head and my back cracked and it just seized up," Purdy, 34, told Erin Andrews backstage. "Everything's really painful right now. It's hard to breathe."
"Sorry we couldn't do our live performance tonight #TeamLoca, but we kicked ass in rehearsal! #PurdyHough #DWTS @DancingABC," she added later.
In addition to thanking all her fans for their support via the social media site, Purdy also gave some insight to what happened Monday night.
"The [doctor] thinks it's muscular, still waiting on the official word," she wrote. "As we walked away from the judging table my upper back cracked and went into spasms… in pain but I'm in good hands."
Purdy, a paralympian snowboarder, is considered one of the runner up contestants in the 18th season of the dancing competition. It's still unclear if she'll be able to compete in next week's episode.
Nene Lakes and Tony Dovolani were eliminated during Monday's episode of DWTS.