I Started Spotting On Monday So I Thought I Had

I started spotting on Monday so I thought I had gotten my period, later on the day I went to change my tampon and it was completely clean. Around 6pm I started cramping and my back was hurting, I went to the bathroom and I was spotting again and around 9pm it stop again. Today I'm going through the same with cramping and my breast being sore. This is the first time this has never happened before. Is it normal? I'm 23 married and we use the pull out method as birth control. I would really appreciate your help because I am freaking out.