Hi, you sound like you are getting bouts of hypotension, are you taking high blood
Also i would get checked for diabetes
insipidus, which can make the urine very clear.
I would go and see the doctor, and tell him what is happening, if you are taking blood pressure meds, this can cause a fall in blood pressure, so be very careful that you dont have a fall, especially being pregnant,
Good luck . wishing you and the baby well.