Spotting AFTER AF

[Freckels]

So I had My period 11/26-11/30 normal except for some reason I took a break in the middle one day no period until the middle of the next day I thought nothing of it. Then 2 days ago I got a killer backache. Everytime I move it feels like someone is stabbing my spine and it still hurts 2 days later. I figured I just slept wrong since I had AF, but today I was spotting. It didnt last long maybe 2 hours. I've never done this before, is it possible I'm pregnant? When AF came I thought that was it for the month. I'm scared to even get my hopes up been TTC for about a year now