Had an accident . after which the recovered skin became dark and my healed wound has a clot like growth.

Hyper immune: The dark skin is from hyperpigmentation, a accelerated response by your body to heal the wound but which also causes the release of excessive melatonin signals that make the cells produce to much pigment. The clot like growth sounds to be similar, look up the term "proud flesh". Both can be controlled by proper utilization of corticosteroids. See a dermatologist.

Probable keloid: Not sure what you mean by 'clot like growth', but it sounds like you have a thick scar that may be either hypertrophic or a keloid. Either way, it may benefit from treatment with steroid injection or a laser. See a plastic surgeon or dermatologist for advice.