Hello,
Skin tags get black when they get rubbed or twisted and lose their blood supply. These will gradually fall off. But if they turn painful, red or are associated with itching and discharge then please get it evaluated from a dermatologist.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
btw, i have been using the blow dryer quite a lot lately on thta area, could that accidentally have affected them?