Try to have a better posture by standing upright. Cos as baby grows the centre of your gravity shifts.
Wear low-heeled not flat shoes with good arch support. Avoid high heels, which can further shift your balance forward and cause you to fall.
You might also consider wearing a maternity support belt.
Try heating pads or cold pack. Light massage at the back is fine too.
Exercises for the back, such as low back stretch, can help ease backaches.
Heres a link to some vids.
https://youtu.be/S3xXurLpfDk
https://youtu.be/sT56d6cJoNA