What Causes Spotting,nausea And Breast Tenderness?

I am esther,22yr old,i took an after morning pill twice in the same month....i got treated for yeast infection n pain on the right side of my lower abdomen..n for three weeks now i have had spotting ,sometimes nausea,breasttendernes,pain in my ovaries..what could be the problem n i took a pregnacy test it came out negative..