I had 3weeks period now what medicine should i take to stop...

Ob-Gyn Dr. can help: For a prolonged menstrual period, especially a heavy prolonged period, a primary care doctor or an ob-gyn can help. The doctor can evaluate to see what the cause might be. Treatment options may include hormonal therapy (birth control pills or depoprovera shot).

See your doctor now: You may have a growth or a hormonal problem & must have a diagnosis before taking medicine.

Further info needed: These may require a more detailed history, with regards to your medication(s), diet, etc. More often than not this should be evaluated further.