I keep feeling a discomfort on the left side near my last rib I think, I don't know from what.Anyone else felt like this?

So for a few days I think i keep feeling not exactly pain, but some stretching of a muscle which causes a discomfort, somewhere near the ribs on the left side, but only when I stretch to the right side.Like this: 1.bp.blogspot.com/.../SideStretchCollage.jpg (except i'm leaning to the other side).My dad started saying it may be a intercostal neuralgia which it isn't because it's not pain and I don't have a rash.And the last physical activity was the PE at school about a week ago.It doesn't bother me when i breath, or walk or anything just when I strecth to the right.Let's say I feel the discomfort where the t-shirt finishes on the right side of the pic (static.ddmcdn.com/.../...-lifting-for-women-6.jpg) , I guess somewhere next to the last rib or upper.I'm asking because maybe some of you experienced this from a physical activity or something.
I keep feeling a discomfort on the left side near my last rib I think, I don't know from what.Anyone else felt like this?
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