Constipation pain

I haven't had a healthy bowel movement in weeks. I am 13 weeks tomorrow. I am having really bad stomach pains, and my lower back and hips are radiating with pain as well and have been for days now. I've been to the ER for it. They eased my pain and sent me home still blocked up. I'm afraid it's at a dangerous point because I am hurting so badly. I take Mirolax and it's not helping. I spend the first 12 weeks of my pregnancy throwing up all the time. Even though my morning sickness has subsided, I realized I have zero appetite, and relate this to my constipation. Please help with any suggestions. I take benefiber and drink water. What do I do? It's to the point I am kinda scared.

Thank you ladies.

~ mommy with excruciating poop pains