Well, I do know why I have one of them ... I caught my leg very very slightly on the corner of my bed. There was a tiny red mark perhaps the size of half a 5p. A bruise has appeared 3" long and an 1" wide.
I have a massive deep purple one on my thigh. On my other thigh one has appeared tonight.
I have one on my arm. On my knee. Two on my leg. All new. All today.
I do an office job. Nothing manual at home this week.
I also (not sure if related) can't stop wanting to wee !
Should I be concerned ? I can see another one under the skin on my upper arm :(