You might need a culture test since hospital borne infections could secondarily infect a well healing wound.
It looks like gaping of the wound has occurred due to wound infection. Swab samples of the wound/incision line have to be taken and sent for culture-sensitivity along with blood culture to isolate the infecting organism.Then specific antibiotics-topical as well as oral have to be started.Till the report of the culture comes,the doctors will start with broad spectrum antibiotics.
Severe cases of wound gaping may require dressings for a longer period of time or even a resurgery to stitch the skin together.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.