Welcome to HCM.
You do not have to be worried about those red spots on your thigh. It will subside and go away on its own.
The spotting that you experience must be due to hormonal
imbalance. Since you are still in your teens, you do not have to worry about it. If you have a heavy bout of bleeding you should consult a gynecologist and get an ultrasound
Wish you all the best.