Hello, persistent nodular acne especially on jawline and chin area in your age is suggestive of hormonal cause of acne. Very stubborn nodular acne is treated with tiny injections of steroid ( ILS therapy) which help the acne to heal faster and also reduces chances of scarring. You may visit a good dermatologist in your area who will suggest you proper treatment after examination. Also you may need to undergo few tests to rule out if there are any underlying hormonal issues. Refrain from picking, scratching the pimples or using scrubs as they worsen the acne and prevent it from.healing and result in dark spots or scars. You may visit my website www.eternisclinic.com/dermatology for more information on acne skin care tips. Hope this helps. Warm regards, Dr Pinanky Jadhav, Eternis Clinic, Pune