I feel something new in abdomen. Feels like a tendon, worried it could be a growth

[JohnKay98]

M, 42, w/back tension & spasms so I often do trigger point therapy on myself, including sides, abdomen, chest, etc.  Sometimes I massage my abdominal area and a few weeks ago noticed something I've never felt before.  It feels like a ligament or tendon (but I don't know).  It's under my skin (and perhaps fat and/or muscle).  I can feel it with my fingers, but to feel it clearly I normally need to use lotion. The part I can feel runs from the bottom of my left ribcage, approx. 2 inches from the center of my abdomen.  It runs down through the abdomen, just left of center, and I can't feel it once I get to the fatty part of my belly.  There is no pain from this, neither when I touch it or leave it alone.  I'm assuming it is a tendon or muscle of some kind that I've never noticed, but never felt this before, wondering if it could be something else.  I scheduled a Dr. Appt, but it's my annual physical and it is almost 2 months out, wondering if there's someone who aced muscular anatomy who can put my mind at ease