I found a hard bump under the skin on my vulva. what could it be? i am 20 years old. the bump is new.

This : This is likely a cyst, or possibly an infected hair follicle. The only way to know for sure is to see your family doctor or gynecologist for a complete examination/evaluation. In the meantime you can try soaking in a warm bath with epsom salt three times a day. Only put enough water to cover your buttocks. Also try Ibuprofen for pain if present and to help with inflammation. Best of luck.