What is this new dent in my cheek and how can I fix it? (Photos)

It depends on what has caused these depressions. From what you have posted, it doesn't appear as if you have had an injury to the area. These areas of depression can potentially be made less obvious with either fillers the effects of which are temporary and last for about 6 months or your could have fat transfered to the area which is permanent. You do need to assessed in person to determine the best option for you. For optimal outcome, please consult a fully qualified plastic surgeon, who has specialist qualification in plastic surgery 'FRCS Plast' after having being trained adequately in the field of plastic surgery, is registered on the 'Specialist register for Plastic surgery' with the General Medical Council and has been considered competent enough to be a member of the 'BAPRAS' (British Association of Plastic Reconstructive and Aesthetic Surgeons) and 'BAAPS' (British Association of Aesthetic Plastic Surgeons) at the least.

this happens with age especialy with weight changes sometimes its from lower volume in the cheek and sometimes from swelling around the eyes that develops with age (festoons). this will not go away but morpheus RFMN can help, lasers like clear and brilliant and fillers to the eyes/midface.  Peels like cosmelan and at home dermarolling also help (see link to emeragecosmetics.com where we do free skincare consults daily).  Best, Dr. Emer.