My mental health is at stake.. please help!

Michelle • Baby 💗 born 6/11/17 & 💗 born 8/27/19

Over a week of this horrible behavior. My 19 month old will not go to sleep at bedtime. It will take over 3 hours of screaming for her to finally fall asleep in our arms. She was a perfect sleeper until a week ago. I took her to the doctor today to see if she was sick. She’s fine. I need help, my mental health is on the line. I’m pregnant and exhausted 😭😭😭