Both of my hernia's (first one at top of my original incision - above/to left of belly button and second where ileo used to be) showed up on routine CT's. When you meet with your oncologist, just be sure to ask if the report mentions hernia's - if they are there, they will be noted.
If you feel around the area that stings, you might be able to feel a firm "ball" shape too - another good sign of a hernia. My surgeon told me any time they cut into your abdominal wall, it will always be weaker than the "original" you and more susceptible to hernia's.
I had my accupuncture therapist work on my scar where my ileo used to be last week and it really helped. She said accupuncture is very effective at helping break down scar tissue. I had a hernia repaired there about 18 months ago and it's just never seemed quite right. One end is still slightly swollen and it gets kind of tender. So far no new hernia's have shown up - but who knows; maybe I've got another one coming.