I had some scars of old acnees on my shoulders, latlely started to get more acnee that will turn to scars. why is that.? can i stop them?

Control the acne: To prevent further scarring you should see a dermatologist for acne treatment options. This will include topical as well as oral medications and skin care. Occasionally surgery or steroid injections are indicated to minimize scars by infected cysts.

Most likely: It could be stress, hormonal changes or dietary changes. See a dermatologist. Good luck from nyc.

Many reasons : There could be many possible aggravating conditions but wary intervention may help to minimize the consequences of scarring by excellent skin care, appropriate topical as well as oral medications and surgery which would be be prescribed under the care of a dermatologist.