Lee, your pain symptoms and location are pretty much exactly what I went through and am still dealing with at a low level. The pain was/is on either side of my mid abdomen, maybe 2" below my ribcage. I can feel a sore soft spot and sometimes a moderate bump in the muscle wall. But not quite a bulge like a hernia. Strange thing for me was that sitting up etc didn't make it hurt more. Just sitting or bending my abdomen made it hurt. It felt like a pressure, sharp cramp type of pain..
And if I lay totally flat for 20 min, the pain would go away completely.
I took 2 weeks off lifting and cardio totally and the bad pain went away.
I started cardio slowly and then added some light lifts and no squats or lifts that would put strain on my core. I tried some light squats last week and the pain came back mildly, so this may be something I deal with for a while.
I think if you can take off physical activity for a week completely you will know if it is a muscle weakness, beginning of an abdominal hernia or something else.
I had CAT scans just to be safe. Sorry you can't get that done as this pain could be caused by other things, and pain is a strange thing sometimes in the way it feels vs where and what it is.