I Stopped Taking My Birth Control Pills 3 Weeks Ago.

I stopped taking my birth control pills 3 weeks ago. I had been on them for 9 years. I'm now experiencing very tender nipples as well as cramping. I had what I'm thinking was my period a week ago which lasted 3 days. Is it normal to feel this way?? I took a pregnancy test 2 days ago. It came out negative. What's going on with me?