What would cause a large red puss filled bump on upper leg oval shaped it busted in the middle of night and came out?

A large red puss-filled bump on the upper leg that bursts and leaks pus is likely a furuncle, also known as a boil. Boils are caused by a bacterial infection of the skin and hair follicles, and they can occur anywhere on the body but are commonly found on the face, neck, armpits, and upper leg.

Here are some factors that can contribute to the development of a furuncle:

1. Bacterial Infection: Furuncles are caused by bacteria, typically Staphylococcus aureus (staph) or Streptococcus pyogenes (strep). These bacteria can enter the skin through cuts, abrasions, or other skin damage, or through blocked hair follicles.

2. Poor Hygiene: Lack of proper hygiene, including not washing the skin regularly and not changing clothes frequently, can create an environment that allows bacteria to thrive and multiply, increasing the risk of furuncle development.

3. Skin Trauma: Injuries to the skin, such as cuts, scrapes, or insect bites, can provide an entry point for bacteria and increase the risk of infection, leading to the formation of a furuncle.

4. Certain Medical Conditions: Some underlying medical conditions, such as diabetes, obesity, and immune system disorders, can compromise the skin's natural defenses and make individuals more susceptible to bacterial infections, including furuncles.

5. Poor Nutrition: A diet lacking essential nutrients, such as vitamins and minerals, can weaken the immune system and make the body more vulnerable to infections.

If you have a large red bump on your upper leg that is painful, swollen, and filled with pus, it's crucial to consult a healthcare professional for proper diagnosis and treatment. They may recommend antibiotics to combat the bacterial infection and provide guidance on wound care to facilitate healing and prevent complications.