What Could Be The Reason For Irregular Menstrual Flow And Frequent Urination?

Hi, I took two Ponstan tablets back In August to stop or reduce rather my flow because I was on vacation. My period came just in the morning. Just a light spotting and that’s it for the entire day. September came and my period came normal. October comes and the start of my period, just light pink in the mornings.somw days I would see a dark red color but that’s it. Then some times I would see a discharge of brown, like old blood releasing. I went to my doctor and he said it may be a case of irregular period. I was given some birth control pills to make my flow regular. While on the pill I’m still seeing the light pink spotting. On oct 24 it was a heavy red flow in the morning, but that was it for the day. Then light pink spotting. Then today. The discharge as if old block was releasing. I have a frequent need to urinate and I get tired easily. The irregular flow has been going on for the whole month of October and took a test and I am not pregnant. Can you help me understand my problem?