Pulled Muscle, or Hernia?

How can I tell if I have a pulled muscle, or a hernia, or some other kind of rupture? I have a couple of spots in my stomach area, one of which is fairly large, that are excruciating when I make certain movements, particularly when bending over or pulling myself up. In fact, I didn’t at first think it was a pulled muscle, but rather that I had pinched something because bending over was when I first discovered the pain. The largest area runs vertically, adjacent to and about 2 inches to the left of my navel and appears to be 2 - 3 inches long and an inch wide, judging from the area of pain.
I should probably note that I’m overweight, so a “feel” test of the affected areas doesn’t seem to reveal much, at least not to me, an untrained lay-person.
I wanted to Google the problem, but couldn’t figure out how to approach the search…
So, any of you Doper physicians out there care to take a stab and what I can to do more accurately identify the problem?

Thanks!

The best way to tell what’s going on is to CALL A DOCTOR and MAKE AN APPOINTMENT FOR A DOCTOR TO LOOK AT YOU, and the sooner the better.

The doctors and medical practitioners who participate on this message board are not going to diagnose online.