sounds like normal acne to me, how old are you? i used to get them on my chest, back, top of my arms - basically where my t-shirt covered - along with my face and neck.
only thing that sounded weird to me was the spots on thighs, and it got me wondering; where exactly are they? do you shave anywhere near them? if you do it could be that your pores are open when you shave and dirt gets in.
it could just be a hormonal thing, meaning they might get worse around 'that time' and then settle down in between, but if they do continue (or are just too annoying to put up with) i do suggest a trip to the docs. they won't necessarily put you on tablets, when i went the first thing my doc gave me was a face cream that dried the spots up (and bleached towels!), when that didn't work effectively enough for me i asked about being put on the pill to control my hormones - never looked back since.