What Causes Vaginal Discharge Along With Lower Back Pain And Nausea?

First day of my last period was the 5th of January and my husband and I got intimate on the 15th to the 19th of January and also the 19th was my ovulation day. 3 days after ovulation I have cramps and creamy odorless cervical mucus with lower back pain and light nausea.
What does this mean?