“Jeopardy!” host Alex Trebek opened up about his struggle with pancreatic cancer during an interview with “CBS Sunday Morning,” revealing to correspondent Jane Pauley that early on, his treatment often left him with debilitating stomach cramps.

“This got really bad. I was on the floor writhing in pain. It – It went to – it went from a 3 to an 11. And I just couldn’t believe. I didn’t know what was happening,” Trebek said during the interview, which CBS will air May 12.. “And it happened three or four times a day while we were taping. So that was a little – little rough on me.”

“I taped the show, and then I made it to the dressing room on one occasion, just barely, before I writhed in pain and cried in pain,” Trebek continued. “So – and I had 15 minutes before the next show. So I got myself together and spasms of that kind usually last about 10 to 15 minutes.”

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Trebek also revealed he had lost his hair as a result of chemotherapy and he had been hosting recent episodes of “Jeopardy!” while wearing a hairpiece.

“And so what the challenge for ‘Jeopardy!’ viewers is right now is to figure out, ‘Is that Alex’s real hair, or is that a full hairpiece?’ Because they all know that when you start chemo you lose your hair. So which is it?” Trebek said, before adding after a pause, “This is not the real me,”

Trebek said he hoped his real hair would grow back during the summer recess of the show, but that he had been told at times that his fake hair “looked better” than the real thing.

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Trebek said in Mach that he had been diagnosed by doctors with stage 4 pancreatic cancer. In a customarily stoic announcement, the longtime host said he intended to fight the disease and even joked that he needed to keep going to fulfill his contract — which runs until 2022.

“Normally, the prognosis for this is not very encouraging but I’m going to fight this,” Trebek said. “I’m going to keep working and with the love and support of my family and friends — and with the help of your prayers, also — I plan to beat the low survival rate statistics for this disease.”

Watch a preview of the interview above.