if i were you i would get checked out by your midwife on monday, i am never happy with my gp her answer to everything seems to be that i have a water infection.
The symptoms you have are those of a urine infection, when i had one i had traces of blood and bacteria in my urine, but also pain when urinating. Although if yours has reached your kidneys it would explain the abdominal pains.
Aslong as the anti biotics are safe for pregnant women, it should clear it up in no time. However there would be no harm in being double checked on monday by a midwife, she will check babies heartbeat etc, so even if its just to give you peace of mind.
Hope you feel a bit better soon.

xx