What Causes Vaginal Bleeding Between Periods Along With Stomach Cramps??

I had my period two weeks ago, which I believe it was late. I had sex right after and then a couple days
After and again a week later. Now two weeks after my period ended I am bleeding again, cramping more then normal, I've been moody lately, have pain in my leg side, and my nipples are tender to the touch. What is going on?