At 6 months, this is less likely to be ordinary fresh bruising and more likely to represent persistent discoloration, hemosiderin staining, scarring, or another skin-change pattern after surgery. In the photos, there is dark patchy discoloration, but the cause cannot be confirmed from images alone. Hyperbaric oxygen is usually considered for specific acute wound-healing or tissue-perfusion problems, not as a standard treatment for old bruising many months later. You should be examined by your operating surgeon and possibly a dermatologist or laser specialist. Treatment may involve time, pigment-directed skin care, vascular/pigment lasers, or scar management depending on what the exam shows. If there is pain, drainage, open skin, spreading redness, or worsening swelling, seek prompt in-person care.