hello doc,i am 29 years old,having regular periods since it started.but i always have very painful periods and suffer weakness during that time.initially my periods lasted for a week then it was reduced to 4 or 5 days and now its only 2 days....but i do have enough bleeding in those two days...but i also have blood clot kind of thing in my bleeding which worries me a lot.also my menstural bleeding is brown at start and end of periods.is it normal?