Small lump under skin?

I posted recently pain I felt in my ribs during a horrible month filled with anxiety, it seems to have gotten better but one thing I’ve noticed after it ended was this small round lump under my skin on my left rib cage just below my breast. I was wondering if anyone has this?

I’ve noticed a few other tiny lumps, but this one seems to be the biggest. It’s half the size of a pea and it doesn’t move too much, it feels kinda fatty too. I have health anxiety so I just feel concerned. I brought it up to my doctor and he didn’t seem to care at all, he didn’t even tell me what it could be! My best guess is Lipoma if not that then maybe a cyst or possible a muscle knot(however it doesn’t hurt), but I’m only 19 so I’m not sure if I should be getting those at my age...... anyone know what it could be? Thanks in advance.