Jeopardy! host Alex Trebek isnt holding back about his battle with stage 4 pancreatic cancer.

He told CBS Sunday Morning that his treatment produced overwhelming discomfort on and off camera.

This got really bad, he said in a preview posted by CBS News . (The full segment will air on Sunday.) I was on the floor writhing in pain. It went from a 3 to an 11. And I just couldnt believe, I didnt know what was happening. And it happened three or four times a day while we were taping. So, that was a little rough on me.

Trebek said he soldiered on to avoid canceling production.

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, he said to host Jane Pauley. 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. So, all right, here we go again.

In a clip of the segment, above, Trebek joked about getting a hairpiece after chemotherapy caused his hair to fall out.

And so what the challenge for Jeopardy! viewers is right now is to figure out, Is that Alexs real hair or is that a full hairpiece? he said.

Trebek, 78, said he hopes it will grow back for next season cause I like my own hair!

The recent Daytime Emmy winner had opened up about his treatment last week as well, telling Good Morning America of surges that come on suddenly of deep, deep sadness , and it brings tears to my eyes.

Trebek revealed his diagnosis in early March amid tapings for the show. Filming is now done for the season but new episodes continue to air.