What Causes A Vaginal Discharge With Abdominal Cramps And Breast Tenderness?

Hie i am 24 years old and i was initially on the ocp marvelon and i had breakthrough bleeding for the first week after my first period and then for the first week before my second period. I recently did a full STD test as well as a smear test and a pregnancy test and i was informed that my results were all normal and that it might be due to the ocp i was on. So my GP swapped my pills and now i am on mycrogynon 30 and I was advised to run two packs together so I have not had a 7 day gap between the packs. I have realised that I have had slight brown discharge in the last two weeks off and on. Also I have had slight abdominal crams as if i was getting my period and tenderness in my breast. I have had a vaccination for HPV and during my last smear test they informed me that everything was normal. Should I be worried about the discharge