I've been dealing with constant pain in my lower back and lower abdomen since the end of September after lifting something heavy. It was really bad at first, and I had to stay in bed for about 45 days because moving was just too painful. Now I can get through my day-to-day activities, but its still uncomfortable. On top of this, my periods are now 11 days late, but my pregnancy test came back negative. I'm really worried and not sure what's going on. Could these issues be related somehow, and what should I do next?