Confused

My husband and I are trying to conceive. My last period was nov 22 I ovulated on the 2/3 of dec. yesterday when I wiped I saw a tiny bit of pink blood on the paper. My period isn't suppose to come until the 16 or 18 I took a pregnant test this morning and it was negative. My breast are really sore. However my overies hurt like I'm suppose to start. The blood is what I'm concerned about can anyone help me or has had this same situation?