Vaginal Yeast Infection (Candidiasis): This is a common condition that can occur after menstruation due to hormonal changes and the presence of blood, which can alter the vaginal pH and facilitate the overgrowth of Candida.

Bacterial Vaginosis (BV): BV is another common condition that can cause vaginal irritation. It occurs when there is an imbalance in the normal bacterial flora of the vagina, leading to an overgrowth of harmful bacteria.
Trichomoniasis: A sexually transmitted infection caused by the parasite Trichomonas vaginalis, which can lead to vaginal irritation, itching, and abnormal discharge.
Contact Dermatitis: Irritation or allergic reaction to sanitary products, soaps, or other substances that come into contact with the vaginal area during or after menstruation.

Pelvic Inflammatory Disease (PID): Although less common, PID is a serious condition that requires prompt treatment. It is usually caused by sexually transmitted infections and can lead to severe complications if not addressed.
Cervical or Endometrial Cancer: Although rare, any abnormal vaginal bleeding or irritation, especially in older women or those with risk factors, should prompt an investigation for cervical or endometrial cancer.
Sexually Transmitted Infections (STIs) like Gonorrhea or Chlamydia: These infections can cause vaginal irritation and are critical to diagnose and treat to prevent long-term complications.

Desquamative Inflammatory Vaginitis (DIV): A rare condition characterized by vaginal inflammation and ulceration, often presenting with vaginal irritation and abnormal discharge.
Lichen Planus or Lichen Sclerosus: Rare skin conditions that can affect the vulvar and vaginal areas, leading to irritation, itching, and sometimes scarring.
Vaginal Foreign Body: Although more common in children, a foreign body in the vagina can cause irritation and infection and should be considered in the differential diagnosis, especially if other causes are ruled out.