Is it like a sharp pain? I’ve been getting it on and off from around 12 weeks - it hasn’t come back recently though so I think it may just be the uterus or something pressing against your nerve? Or your pelvis expanding etc
I had this so many times it's so painful. I'll be honest I couldn't do much about it except some very light gentle excercises courtesy of YouTube. Hope it passes for you soon
Sciatica you can literally get it just in your butt cheeks c