I'm Having Brown Discharge But Very Lil Amount But I

I'm having brown discharge but very lil amount but I had yellow discharge this morning but at night it turned out brown also I'm having pain on my right abdomen n it going back to my lower back and also having nausea it happens with me several times before but not regularly it comes n go sonetimes I feel pain at right side and sometimes on the left side and discharge usually comes right after my periods.