Hi,
I am a 23-year-old female. During my period, I sometimes develop small pimple-like bumps that are filled with blood and pus around the pubic area. They are hard to the touch when lightly squeezed between thumb and forefinger, and usually only 1-2 of them appear at a time. They are not painful, just uncomfortable when they rub against tight clothing. They eventually burst on their own, leaving red marks on my skin that do not go away.

I am not and have never been sexually active, so there is no possibility that they are the manifestation of a sexually transmitted infection. However, around 12 months ago I was diagnosed with Hashimoto's disease. Through Chinese medicine, acupuncture and diet I have brought my thyroid function to back within the normal range as evidenced by a series of blood tests , but my metabolism is still lagging, I still experience great fatigue, and my menstrual cycle now seems more unbalanced than any time previously in my life.

What could these pimple-like things be, what are they being caused by, and how can I treat and prevent them?