Shelley (oops - it's a very long reply. Sorry) 

I completly understand how you feel. I went for routine c'scopy because I had Colitis and tumor was detected. I too felt healthy, no symptoms. So it's very hard to get your head around. 

I had 2 options - remove the tumor or remove the entire bowel. I opted for full bowel removal so the Colitis wouldn't cause a further tumor, plus less complications with full removal compared to cut & resection option. Full removal has left me with an illestomy bag. I've had it a year and do far its been grand. Finding clothes is probably the worst part. Not everything fits comfortably with the stoma bag.

After my op, I had 8wks to recover before I had 4 cycles of chemo.

You will likely be sent for a CT scan - this will show the extent of the tumor/ if it's anywhere else. You may get a PET scan and MRi. I didn't the 1st time.

When you get your surgery, make sure your consultant checks your bellybutton. Sounds weird, but mine looked distorted. My consultant did check it at every appointment and even had it biopsied as if wasn't looking normal. Turned out to be cancer tumor!!! After all the scans, it's spread to a few places so no surgery just chemo.

My advice to you ask loads of questions. If you have to write down the info. My consultant let me take a photo of my scan results. Take some one with you to the appointments, moral support and for some one to ask questions you may forget. Don't always trust Dr Google or chatgpt - they don't always get it right.

If you need me, I'm here. Literally be lying on the sofa in chemo recovery mode lol. 

Take care & I'll be praying for you x