Has this happened to you?

Jessica
I am currently 6 dpo and I have been getting these intense leg and back aches. It feels as if I ran a marathon. I have not excersized nor done any heavy lifting. It's so bad it keeps me up at night. Also, light cramping off and on for like 2 days now. I'm not due for AF until 4/15 so it's quite early for period cramps. Idk what to think. Could it be an early pregnancy sign?