What Causes Tiny Purple Bruises And Red Lumps In Between Buttocks?

I keep getting these perfectly circular tiny purple brusies towards the bottom of my butt only by my butt crack. I also keep getting these painful red bumps that have no head but are solid and dime sized, also only in one area. They last for weeks at a time, go away and them come back, but they are verg noticeable. Ive only noticed having them the past 6 months. There soooo unattractive, help?