Derek Hough recently explained why he was so "grumpy" last week on ABC's Dancing With the Stars.

Will Alek Skarlatos Or Carlos PenaVega Be Eliminated In The 'DWTS' Semifinals?

Hough, who wasn't exactly in a cheery mood during his and Bindi Irwin's rehearsal package in Monday night's episode, revealed the whole story in his TVGuide.com blog.

The pro dancer had been battling strep throat and swollen glands.

Bindi Irwin: 'DWTS' Partner Derek Hough Has 'Changed My Life'

"Last week was such a difficult week, so I'm really happy to get through it. You saw a lot of grumpy Derek, which was pretty accurate! I was actually sick last week," he wrote. "I could barely talk and my glands were so swollen. A lot of the time, I felt such a block. Everything for me is based on feeling. If I'm not feeling physically good, I don't like anything I come up with. It's one thing to learn something, but to create something when you're sick is a really difficult thing to do. And of course traveling to New York was a lot. But Bindi was wonderful and so positive, and everything turned out really well. I'm really proud of the dances and how it all came together."

He and Irwin are performing three dances for this Monday's episode: an unlearned dance (Salsa), a Samba dance off against Nick Carter and a jazz trio with Mark Ballas. However, Ballas apparently damaged his foot this week!

But Ballas had indicated that he's excited for the dance, so it seems like he'll be able to perform by Monday's show. Hough is excited about the story behind the dance.

"The story is about how we isolate ourselves and we get imprisoned by our own issues and how we're all connected and we're bonded together. So we're gonna use a rope and at the end of the rope is a light bulb. We're gonna use this rope to move us around. Now I have to see if it's possible to do it, so we'll see!" Hough wrote.

Dancing With the Stars airs Mondays at 8/7c on ABC.

Tags: Dancing with the Stars Reality TV ABC