What are the dark hard pimple like knots that form under then skin between your thighs?

The dark hard pimple like knots that form under the skin between your thighs are called ingrown hairs. They occur when the sharp tip of a hair grows back into the skin instead of out. This can happen for a number of reasons, including:

* Shaving or waxing too closely

* Wearing tight clothing

* Having naturally curly or thick hair

* Having a skin condition that causes inflammation or irritation

Ingrown hairs can be uncomfortable and unsightly, but they are usually not serious. They can be treated with a variety of methods, including:

* Applying a warm compress to the area

* Using over-the-counter or prescription medications to reduce inflammation and pain

* Carefully removing the ingrown hair with a pair of tweezers

If you have a persistent or severe ingrown hair, you may need to see a dermatologist for treatment.