Lower abdominal pain
is quite common at this stage of pregnancy
. If any serious causes of pain have been ruled out (which seems to be so in your case), then the pain is likely to be due to stretching of the structures around the uterus
as the uterus enlarges with the pregnancy. Although this can be uncomfortable, it is nothing to worry about and not much can be done about it. It should get better with time.
The hormone progesterone
is produced during pregnancy which can dilate the pelvis(like a sac) of the kidney
. This again is frequently seen in pregnant women and is not a cause for worry. You do not have a urine infection and this is a good sign.
Hope this answers your query.