A 35-year-old woman complains of frequent, painful, difficult urination, constant urges to urinate, and several drops of blood appearing in her urine at the end of the process. She fell ill suddenly, after overexposure to cold, when the complaints above appeared. Body temperature - 36.6°C. During palpation, pain is observed in the area of the urinary bladder. Ultrasound shows a small amount of urine in the bladder, the walls of the bladder are edematous and uniformly thickened. Urinanalysis detects leukocyturia (30-40 in sight), proteinuria (0.099g/l), and erythrocytosis (5-7 unchanged erythrocytes). What is the most likely diagnosis in this case?