Really bad pain

Stephanie • Boyfriend: 12/29/2014 - Forever :) Baby Boy - 09/25/2016 and pregnant with baby #2 due 11/20/2017
This is my first pregnancy so I always have a lot of questions lol. Do any of you know what this pain could be that I'm feeling in my left thigh and lower abdomen? I'm 12 weeks and 3 days pregnant and all day today I've had this on and off pain and it hurts really bad :(