What Could Be Causing Unexplained Hickey-like Marks On The Backs Of My Legs, Thighs, And Hips Appearing Over The Past Two Years?

I m a over weight female age 37 and I don t know what s going on but I tried to commit suicide 2 years ago by slitting my wrist timid arm had surgery but was so out of it I was at mental health before waking not long after I returned to my state I lived in I started getting hicky like marks on my legs thighs and hips but o ly from back side and the longer it s been the more they pop up please it s important I find out thank u