What Causes Dizziness And Fatigue In An Obese Person?

Hello doctor,i m over weight ,my problem is when i pass urine ,i feel like (dizzyness)fainting and my throught just became very dry ,like no energy in my body ,so my doc. Suggested me to go for urine test ,but now my doc. Is out of station not picking call, So i m confused that which urine test should i go for (simple or culture ) if it is culture than which type of culture test ,plz advice regarding my problem ....thank you