What Causes Black Pock Marks Under Skin Flaps?

I have a friend who is obese (just under 300lbs and 5" 5"). She had emergency surgery back on March 27 for a strangulated hernia. She has since been recovering - though not well, and has a series of different infections - both in her open wound - which is still open and not healing, and elsewhere - thrush, UTI, infections under her belly roll. Her latest infection or whatever it is, is happening under her breasts and under her belly roll - black/bloodied rash where holes are opening up in her skin. Initially, it was just under one breast, but now she has a hole opening up under the other breast, first breast has black poc marks the size of a US quarter coin, and the same rash is now all under her bellyroll.

Her health aide has daily been washing and drying and putting on medicated powder. She was put on a anticbacterial cream when she was in the nursing home (for 6 weeks) when she had a different infection under her belly, but that made it worse and she ended up with hives.

My poor friend has been suffering so much since her surgery in March and is not healing. There is now the possibility that she may be allergic to the synthetic mesh they used for the hernia, as the hole was so big they could only use synthetic.

Do you have any idea what could be causing these black pock marks under her skin flaps. they are very painful. Her doctor thinks its a yeast infection and she's been on antibiotics for it for 2 days, but it's got worse not better.

Any suggestions?

Thank you for any help you may be able to offer.

Jan B.