Extreme cramping and really bad nausea

Megan
Everywhere I read says either your pregnant or your not! I am not sure what to believe. 
I am currently 4DPO and have been experiencing cramping from day of ovulation. I am so tired and have sore muscles through out my pelvic region. I have had a couple headaches and I am beyond thirsty! I am trying to get pregnant so we have been trying all the cycle. Could I be pregnant?