You seem to have developed some infection. You need to clean the area with an antiseptic lotion and apply a broad spectrum antibacterial cream and dusting powder. Also, it would be best to apply gauze over it if you need to go out. You can change the dressing every time you pass urine.
However, it is difficult to say whether it is simple bacterial infection or you have even caught a STD or fungal infection. Hence, do consult a doctor and get this examined.
Thank you so much! I will do this!