Upper back left side pain

Ash. ttc baby #1 with pcos

I know this isn't the right group but it's the only group that I get replies So I started af in the middle of the night after my period being late and I've woken up and the top left of my back is in so so much pain I can barely move my arms or bend down. Does anyone know what this is or is it just normal ive only ever had it a few times before xx