The 23-year-old professional dancer suffered a rare and potentially-fatal condition called hyperparathyroidism due to a tumor in his neck that was disrupting the balance of calcium in his blood, People reported.
An endocrinologist therefore had to remove the tumor and check whether it was malignant cancer or benign.
"They said it was a miracle that the doctors found it because most people don't understand they have it until they break a bone or they get kidney stones. It was like all of my stars up there in Heaven watching over me," Alan told the magazine.
Alan was on tour with Dancing with the Stars: Live! three weeks ago when he started to experience sharp pains in his stomach that would last for about a minute and then fade. Alan therefore had doctors run some tests at an Urgent Care facility, and they discovered a high level of calcium in his blood.
"At first [the doctors] were like, 'Oh, it's probably not a big deal. You're probably just taking some supplements,'" Alan recalled. "I went back on the road the next day, and my stomach stopped hurting."
Though Alan said he felt "fine," his caring mother insisted he get another blood test just to make sure everything was okay.
One week later, according to People, Alan learned about a tumor on one of his four small parathyroid glands in the neck. Such glands produce parathyroid hormone, which helps control the amount of calcium in the blood.
"Just the word tumor is so frightening," Alan admitted. "I didn't know what malignant or benign meant until I looked it up and I was like, 'Well hopefully it's benign -- God forbid I have cancer.' That is more stress than I could ever imagine. I think the scariest part was not knowing."
One day after receiving his diagnosis, Alan flew to his hometown of Minnesota and visited an endocrinologist at the Mayo Clinic.
"Unfortunately the only surgery available was on April 11 so my mom quickly was like, 'You don't understand, he has to be on Dancing with the Stars. Is there anything we can do?'" Alan revealed.
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A surgeon therefore decided to squeeze Alan in the very next day.
"If they didn't have a surgeon available," Alan revealed, "I would have had to wait for this season to finish and then do it. I would be so in my head about it, I would be scared. So I got very lucky that they had time and that I was able to recover in time for the season."
Alan had to go through four hours of nuclear testing beginning at 8AM, before going under the knife for two hours to remove the tumor, according to People.
"That type of surgery usually is very short but they had to make sure that it wasn't cancerous," Alan said. "I woke up like 2 hours later like, 'Where am I?' I've never had anesthesia before."
Luckily for Alan and his loved ones, the tumor was benign, and the chances of it coming back in the future are very slim.
Alan also had a quick recovery time of only one week, and then he resumed his busy Dancing with the Stars schedule in Los Angeles, CA -- with caution, of course.
"I met my partner [Olympic figure skater Mirai Nagasu], and it was like a new life. I'm so lucky that everything went so well for me, and I got a partner like Mirai," Alan said.
If the condition was left untreated, Alan reportedly could have experienced memory loss, fatigue, and muscle aches.
Alan now has a one-inch scar on his neck. He was initially self-conscious about it and attempted to cover it up by wearing turtlenecks -- even in the California heat -- but now he's learned to embrace and rock the scar because he's a survivor.
Alan also learned from his health scare that it's important to have yearly checkups.
"I hadn't been for 4 or 5 years, and I definitely learned a lesson from that," he told People.
"It didn't even seem like I was careless, I just never thought about going to the doctor because I was always so young and so active. It's so important to monitor your body because the slightest thing can change your life forever."