advice needed

my mother constantly during summer points out my scars, she figured out that i do self harm and as my mother is normally she is worried for me. i don’t know how to tell her that im so uncomfortable with her pointing my scars out, they are not large scars although she finds it necessary to talk about them. for example we were at the beach and i was just helping my younger brother make a tiny sand castle when she walks over to me and points to my arm, she asks what it is, it was obviously a scar and it was not a previous scar (at the time it had been august and i made the scar last november) i told her it wasn’t a scar i made recently and she would’ve believe me. i notice shes always looking at my thighs and arms when im wearing clothing that reveals that.

can someone please tell me what to say to her to make her stop saying that,thank you.