What Causes Hot Sensation In Thighs After Using Vibration Plates For Toning Body?

Hello, I have a concern. I regularly use vibration plates for toning of the body. I've never had any problems before however, today I noticed that my thigh/inner thigh area was rather hot when I'd finished the ten minutes on the machine. I took no notice of this but later found a small area on both thighs (about the size of a penny or two) with red dots. It doesn't look like normal bruising, doesn't hurt, itch, there are no symptoms. They as much as i recall, appeared after the session and not before. I did not bang myself anywhere. I was wondering if I should be terribly worried about this and consult my doctor first thing in the morning? Medication wise I only take the contraceptive pill and have no underlying conditions known.