Skin dimpling on breast only when arm is raised, started after lifting weights. Freaking out

Hi everyone, I am a 19 year old female and I am absolutely freaking out. About a month ago, right after doing 3 days of arm/chest exercises with 2kg weights, I noticed a skin dimple/line on my smaller breast. It ONLY appears when I lift my arm up and look from a certain angle, and disappears completely when my arm is down. While lying flat on my back with my hand behind my head, I can feel a small, firm, immovable spot right under where the dimple forms. However, when I stand up, everything feels soft and it completely disappears. No stone hard lumps, no changes in over a month (pictures look identical). It feels slightly tender like muscle soreness when I flex my chest. I'm so scared :( Could this just be a tight Cooper's ligament or a muscle trigger point from the workout? Has anyone experienced this? Thank you!