What Causes Bruises On Legs And Stomach?

I am 39, female, 5'6", 290. I have a 4 yr old daughter, only child. I stand on my feet working as a hairstylist, many times, 8-12 hrs a day. I have many bruiselike spots (quarter size mostly) on my legs. I know it is from standing without support hose, however, now I have one on my belly. Is it just my fat doing it? I am not very active and I know I need to get active. Should I be worried, as these have multiplied in the last year or two.

Thanks