The dark marks that you have need to be assessed if it is just pigmentation after the hair removal or the ingrown hair is still present.... because if the hair is continuously there the ongoing irritation will keep making the dark mark recur over and over. You will have to be properly assessed with few hormonal test to know why you have ingrown hair happening along the jawline. For now you can temporarily use kojic cream which can help decrease the pigmentation but it takes time. I would suggest to not delay a proper assessment by too long. You can get an online consultation for me to dermatologist directly. Hope this is helpful.