Thanks for posting this pic. That's exactly where it feels like someone punched me hard with their knuckle sticking out. Happened after a bootcamp workout, followed by 30 mins in a batting cage. It was a sudden discomfort that became worse after I cooled down and especially after waking from a nap. Then I was surprised for find that I felt it while breathing and certain movements reminded me it was there as well. I have no idea what I did but I'm getting a better idea after reading this and some other blogs and websites. It was the twisting of batting that did me in after simply overdoing it.
I did ice it and it felt better the 2nd night. At that time I hadn't yet done my research so I did some band exercises while at work. Nothing major. A couple hours later and I realized that was a not the best thing because the discomfort came back worse than before.
I have that area wrapped with a "Ion Band" (attaches with velcro) that's actually meant for lower back support. It does help a little but I'm really concerned about keeping my bootcamp workouts going!! I'm gonna try. I know the difference between discomfort and pain and I'll stop for the latter. I have a high tolerance and I'm focused on keeping my workout momentum moving forward.