Do I have pseudo bursa after my tummy tuck? (Photo)

I had a tummy tuck surgery about 5 months ago which resulted in having a sizable black tissue between my bellybutton and the incision, the doctor removed the black thick skin and we started using local antibiotics - the dead tissue is still healing but the color of the skin is very red to brown. I am not sure if my belly is swollen or the doctor did not tighten my stomach muscles enough. What is the reason for the dead black tissue and why my belly looks that I did not have a tummy tuck?