My Boobs.. 😨😨

My boobs have always been about a size B ish, not important rn but they’re also really clear like free of any stretch marks etc, usually maybe some little pimples from like boob sweat or a bad body wash or whatever but NOW recently I’m getting stretch marks! All above my nipple area and on the sides by my armpit by your like “armpit fat” and idk why! I’m not pregnant & im not really gaining any weight, EVEN when I did gain weight, they didn’t grow 😒😤 but idk why they’re showing up now?! Also in my inner thighs but those did grow from weight gain but I’m not gaining weight anymore so I’m not sure why they’re showing up now, what can I do to like prevent them & get rid of the new ones? Any product recommendations or whatever ? Thanks 💕💕🥺🥺