Fatigue is no joke and 14DPO

As

I'm 14DPO and I tested negative this morning. All day yesterday (and already this morning) I felt so fatigued. I took a 90 minute nap and still felt exhausted. Every movement I take makes me feel so tired. I've been cramping for the last week as well. I've never had this before. Has this every happened to anyone and then get their BFP this late or before their period? I've never ever felt this way before my period.