Hi,
It might be either an ingrown hair, or a cyst? Both are common, and often go away on their own. You can do a little online research about cysts, such as Bartholin or sebaceous, and compare the similarities to yours. If it continues to bother you, make an appointment w/your doctor or gynecologist for an exam.
Take care
I was shaving Almost anytime Hair was a current Length.
I wear alot of Victoria secret underwear and I know their was said bad Chemical's being used.
I also wear alot of Yoga pants for the most Part.