What am I feeling? Plz read

Kendra • Mommy to 5 boys💙 married to my best friend 💍😍
So I'm on cd13 and been having lower andomin pain for 3 days now. CD 11 I had period like cramps but mild, then on CD 12 I had lower andomin pain and backache, and today Cd 13, I've been having lower abdominal pain all day. What could this be???
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​ ((My 6 year old says maybe your bones are or hurting or maybe you heb a baby in there !?! Lmao))