Hi , greetings! Pimples and marks after pimples are common in teenagers due to hormonal changes and sometimes can occur in mid twenties and thirties too. Further stress and environmental factors could cause you to have more pimples. You need to reduce junk food, increase vegetables and fruits in your diet. Use a salicylic acid based face wash. Also see a dermatologist for prescription of retinoid and bpo based creams and some tablets if necessary.Let me know if you need any further assistance in this regard. Warm regards.