Hello
What do you mean by thick blood , nurse told you that the blood is thick and your girl might have 
HIV infection.It is ridiculous .
Blood in the urine may be due to these reasons , these include:
1 Calculus anywhere in 
urinary tract system as this is the most common cuase of blood in urine . Diagnosis can be confirmed by 
ultrasound of urinary tract system organs .
2 
Pyelonephritis as this is the most common cause of blood in urine along urine containing pus cells . Diagnosis can be confirmed by urine culture and sensitivity test .
3 Cancer anywhere in urinary tract system. Diagnosis can be confirmed by 
MRI of concerned organs .
However, there are other so many causes of blood in urine like blood disorder or if female having menstrual cycle .
In my opinion don't worry , please get in urine culture and doctor will find out the reason of bleeding in urine ( thick blood may be clotted blood from bladder or due to menses cycle .
At least in my opinion neither  this is not a case of HIV infection nor a cause of concern ,nor  symptoms of any HIV infection.
Good luck.