Because of illness, hot weather and sweating, I found the skin on my back festering.

According to what you said, there is skin ulceration on the back, probably bedsore or secondary bacterial infection.

Suggestion:

It is suggested that patients should first pay attention to keep local skin wounds clean, try not to eat spicy and irritating food, go to the hospital for surgical treatment in time, and carry out debridement treatment in time after being diagnosed by doctors, such as washing with hydrogen peroxide or normal saline, disinfection with iodophor, and external use of Dragon Ball Ointment or Clindamycin Gel. Pay attention to keep local skin wounds clean in life.