Air Bubble? Or Cancer?

I mentioned before the problem of wondering whether every new ache or pain is just a routine ache, or something connected to the cancer. I had a particularly egregious example of that today, in that today's new pain was in my side.

Now had I been running, I wouldn't have thought much about it, as the pain has a lot in common with the side pain I experienced in elementary school, junior high school and high school PE* when the teacher made us run laps. But I wasn't doing any running today. Rather, the pain appeared as I was walking (slowly) between buildings after sitting in a meeting at work for an hour. So I'm not sure I can blame this one on exercise. 

More concerning, the pain was located pretty much where the Google images I've found of the human torso suggest my liver ought to be. 

Happily, the pain went away; then unhappily, it came back. And then it went away again, and then it came back, and it's cycled that way a number of times throughout the day. I must admit, it's sort of starting to freak me out. 

If it's still there on Wednesday, I'll be asking the oncologist about it. 

* PE was never my subject.