Working out and back pain.

I had a D&C almost three months ago due to a molar pregnancy and ever since then I’ve had lower back pain. Some days worse than others. But I decided to lose weight just so I can feel better day to day. I walk/jogged on and off on the treadmill yesterday for around forty minutes and then did crunches, squats and all that good stuff after. But my back after was horrible. It was stiff all day and I couldn’t bend over or sit down without taking a long time to do so. It was horrible. Today I feel better but I don’t want to have to workout one day and then not the next bc my body is in pain. Any suggestions on different workouts or what to do about my back pain? The workout wasn’t intense at all