Hello there and thanks for posting

Back pain is a very common ailment and usually is caused by a muscle strain or injury. There is more about this here.

Occasionally back pain can have a more serious cause which is why it is important to get worrying symptoms that aren't going away checked out.

Pelvic masses can cause a range of different symptoms and one of these may also be lower back pain.

Your GP can assess you and if needed arrange more tests to find out more.

I hope this helps

Take care

Naomi