Your concern is well-founded. Change in the colour of a mole may be a sign of skin cancer
. Your cough
and breathlessness may be the complications of excessive smoking
or due to extension of cancer to the lungs, or both. There may be secondary lung infection
as well. Hence, please consult a doctor as soon as possible. And whatever turns out to be the cause, you will definitely benefit from cutting down/quitting smoking.
Best wishes. Take care.