The doctor said I was pregnant then...

Me
I went to the ER yesterday because I had been having severe cramps since 2 AM that woke me from my sleep. They gave me a urine test and it came back positive. Good news! So they took 4-5 viles of my blood and brought in the ultrasound equipment and the stuff for a pelvic exam to figure out why I was bleeding if I was pregnant and then hooked me up to a bag of saline. So about 40 minutes later the doctor came back and said that the blood test was negative but he's not sure why the urine test would be positive because it's more common to get a false negative than a false positive. He goes on to say that the lab may have read it wrong.. They wanted me to do another urine test but I had just peed like a minute before they came in requesting another test. 5 minutes later I took the second test and it came back negative.. So the doc said two negatives outway the first positive but I feel like the saline could have diluted my pee because it was very pale on the second test and looked more concentrated on the first... My period is also light. What do you all think??