Yesterday, I Noticed I Had Bruises On My Thighs, (inner,

Yesterday, I noticed I had bruises on my thighs, (inner, just above knee). Three or so on each side..symmetrical in their placement, ranging from 1-2.5" in diameter. They are the same color. Really oddly shaped.Oh, and there is a random grouping of smaller bruises on the backs of both my calves. I am fit, but haven't been as active recently..there is no activity I can think of that could have caused this.. What could it be?