What Could Be The Cause Of Sudden Eruption Of Bumps Over The Body ?

I have been experiencing some odd red bumps on my arm, chest, back and pelvic area. At first some of the bumps resembled acne and i had poped two of them, wich scabbed over, healed and are still present. The bumps are eraser sized except for a lager one on my back which is about the size of a nickel. They do not itch or hurt. mild irritation when I accidentally scratch them. Some (the more older spots) resemble a blister or burn after it has scabbed over and looks like scaring. What concerns me is one of the first red bumps started underneath a mole I have below my armpit on my side. I have looked for bed bugs, and have found no evidence of them. They started to appear about 3 weeks ago and seem persistant, none have gone away. To my knowledge I have not exposed my self to any new substances that may cause an allergic reaction, same soaps and detergents. Any thoughts?