Unknown cause of pain


My back has been in excruciating pain for about 2 days now. I do not like taking medication and I don’t remember the last time I did but the pain was so bad I just took two Advil. I have a very high pain tolerance and I am not a complainer when it comes to pain. Is there any connection with this pain and a very early pregnancy? What could be causing this pain? I feel it in my lower back towards my left side.