'OutDaughtered': Danielle Busby Shares Her Fears About Her Mystery Illness (Exclusive)

'OutDaughtered' airs Tuesdays at 8 p.m./ 7 p.m. C on TLC and can be streamed on Discovery+.

Danielle Busby is searching for answers.

The OutDaughtered star has been dealing with a mystery illness since November, and now fans are going to be seeing her journey as she attempts to figure out her health issues. In ET's exclusive clip of the TLC show's upcoming episode, Danielle shares the moment she knew something was wrong.

"I knew it was serious because I've never felt this ever in my life. I didn't know if I was having a heart attack," the mother of six tells cameras. "I literally felt like my arm was literally going to explode. That's what it felt like inside."

In an effort to better understand or diagnose her chronic symptoms, Danielle shares that her husband, Adam Busby, suggested they go to the emergency room. In her mind, she couldn't help but fear her illness' impact on her relationship with her kids. The couple are parents to 9-year-old daughter Blayke and 5-year-old quintuplets Ava Lane, Olivia Marie, Hazel Grace, Riley Paige and Parker Kate.

"You instantly think about your kids. That instantly just rushes into your head," Danielle expresses. "I still have a lot of life that I want to live with them, and am I not going to do that anymore?"

Danielle admits that she wondered what she was doing "wrong" to allow that to happen to her body, as she goes on to explain her symptoms and what doctors told her.

Watch the full clip in the video above.

ET spoke with the Busbys about where Danielle's heath stands, revealing that they still don't have solid answers.

"I'm looking at a possible autoimmune disease, and sometimes that's just not easily defined. I'm just kind of having to go through a lot of the same processes over again, restarting different routines of blood work and everything," Danielle shared. "We've always kind of lived a healthy lifestyle. I'm just trying to really look into foods and [figure out], 'How do I eat differently? Could that help with inflammation?' 'Cause there's certain foods that underline with inflammation and everything. It's really, 'How do we maintain your pain level and what you're going through until we can discover what the underlying issue is?'"

She added that for the time being, she has prioritized her mental health, telling ET that she turns to her love for fitness and inner spirituality to "help keep my mental state aligned."

"It can go off in waves," she said. "You can get stressed out real easily in this house. With fitness, which is always a mental blocker for me, I can just zone out and stuff. That's always something I try to keep on top of, and then just my spirituality."

Hear more of what the couple told ET, including if they are looking to have more kids in the future, in the video below.

OutDaughtered airs Tuesdays at 8 p.m./ 7 p.m. C on TLC and can be streamed on Discovery+.