What Causes Purplish Bump On The Waist Line?

i have a purple size of my finger tip bump on my stomach it hurts when squeezed but nothing comes out had it for three weeks now another bump beside it that s red all located on my waste line im a little over weight but not much also noticed a lump on my back size of a grape it don t hurt and is not discolored the one on my stomach is worrying me it gets flaky as well i get these from time to time around my personal area as well during my menstrual