5 weeks pregnant (6th child) but constant period like lower backpain, tilted womb could this be the cause? x

Speculative: Mid-twenties female with 6th pregnancy and low back pain likely has pain generated by hypermobile sacroiliac joints (sij) caused by pelvic mass, secretion of ligament-relaxing hormone relaxin, and 5 prior pelvic mechanical insults. Joint hypermobility syndrome (see brighton criteria) might potentiate this. An sij belt might help, ; an ostetrician should be consulted for other possible causes.