Whipple's procedure

Hi.

My Dad had whipple's procedure 6 months ago, and is currently on cycle 7 of 12 of chemo to "mop up any cells" as the doctors put it.

He's been feeling rough from the chemo but managing it. He's also been managing his creon tablets well and eating a normal diet.

After cycle 7 of the chemo he's not been well at all. Gone off of his food losing weight and diarrhea. I'm terrified it's the cancer back. Has anyone else experienced this or have any advice. 

Thankyou.