On the fifth day after a full-term birth, a postparturient woman developed a fever of 38.8°C, abdominal pain, and general weakness. Her blood pressure is 120/80 mm Hg, pulse is 100/min. The breasts are moderately distended. The abdomen is soft and participates in the act of breathing. The uterine fundus is located three finger-widths below the navel. Vaginal examination shows that the cervix allows inserting one finger; the uterus is soft, painful, and enlarged to 13 weeks of pregnancy. There is a seropurulent foul-smelling discharge from the genital tracts. Make the right diagnosis: