Suggest Remedy For Irregularity In Periods And Brown Discharge After Sex

For about 1- 1 1/2 year now, I have been having overly long periods which last for about a month and a half or more. Sometime it come for for days and would be back the next week. am just confused, I don't know what to do and am worried that this is some sort of infection. Also for the last month a day after sex with my bf, i would see a brownish color (like dirty blood) that would eventually get pink and the reddish.... any ideas why this happens... has happened two times so far...