Dark skin and "track" marks after UAL (Photo)

I had UAL (ultrasonic assisted lipo) 14 months ago. 2 liters of fat was removed from my abdomen and plank area and had some "ab etching" done. Early on, I started to notice skin darkening along what I assume is the path the canula took. I visited with my PS to chat about my concerns and prescribed me a skin bleaching ointment to use every other day, but I am reluctant to use it until I get a second opinion. Any other ideas on what could cause this kind of unevenness and discoloration?