Scabs I don't know where they came from?

I sometimes get scabs in weird places were I wouldn't get the chance to get cut. I get them on the outside of my thighs near my and I just noticed some on my back, like a little bit under where my bra's waistband is. They just seem to scratch right off if I scratch them, but they just come back. I also sometimes get them on my arms and legs. I thought maybe it was psoriasis but they look nothing like any types of psoriasis. They look and feel just like regular scabs. Does anybody know what it could be?