Welcome to HealthcareMagic forum.
and distended abdomen are not related to each other unless there is intestinal obstruction
is another instance but the distension is gradual and slow.
As per your description, the right lower back pain
is most likely related to renal stone or related to menstruation
and the abdominal distension is probably an incidental occurrence.
Are you constipated? Is there any inability to pass stool? - If the answer is yes, then intestinal obstruction needs to be ruled out.
My suggestions that can help you are:
1. Monitor the progress of symptoms.
2. You may take over the counter analgesics for pain relief.
3. Drink plenty of water.
4. Visit your doctor if the symptoms get worse or if you have bowel disturbance as mentioned above.
Hope this helps.