What is going on?

Ha

I am having the WORST lower back pains right now. The last time my back hurt this bad, we had just been in a car accident. I want to take a pain reliever but idk if I might be pregnant or not. I have have food adversions, nausea, tender heavy breasts, cramping at 9dpo, currently 13 dpo CD27/29. AF due Friday. BFN this morning with FMU. Is AF coming with a vengeance or might I be pregnant?