The brown is just a bit of blood that's sat around long enough to rust and change color. You spotted a tiny bit before getting a full period, and the first bit out is now brown. My period occasionally itches a bit. If it keeps itching, you'll need to get checked for a yeast infection (especially if you get thick white discharge).
Why are you afraid to visit the doctor?
The brown discharge is normal, especially if your period is about to be due. As for the leg pain, is it like muscle pain? Could you have done something to pull the muscle?