I'm not pregnant, so why am I so nauseous?

For the past 3 days my back has been hurting really bad. I kept asking John to massage it and he could never really reach where it hurt. It took me 3 days to realize, this was the same 'flank pain' I had when my kidney was hydronephrotic during both pregnancies. It got worse last night, and I started to get nauseous. All I ate was brussel sprouts at ~3pm, and progressively felt too sick to eat dinner.
John had duty today so thankfully my mom cancelled her tennis match to babysit. I couldn't find a urologist that was accepting new patients/could see me today, so I went to our general family doctor. I sense he already doesn't like me since I don't fully vaccinate L + O, but he also seemed to write me off as a hypochondriac. I hate when they ask you about your pain on a scale of 1-10--you know they are going to discount a few points, and while my nausea isn't a 9 or 10, it is a dull constant pain that makes me incapable of doing many things, not to mention caring for 2 babies.
So obviously to appease me, he sent me for a CT scan. He tested my urine and it was very concentrated, so he suspects infection..but I have no symptoms of a UTI, so I think my right kidney is infected. Even when I was pregnant with lucas, my right kidney always hurt. He prescribed antibiotics and I left to the imaging center.
I just got a call back with the results and I in fact have several small kidney stones. TWO ON EACH SIDE. The biggest is predictably in my right kidney and is 4mm. Reading the excruciating pain of passing even these sized stones, is terrifying. You always hear it's worse than childbirth. My mom passed one back when I was little and agreed that it's the worst pain. I am wondering what is causing my body to create them, but I have been eating healthier ever since I found out I had high cholesterol back in 2005. Especially since having had Olivia and we stopped eating out. I only use 'smart balance' butter, skim milk, brown rice. wheat breads. Primarily drink water.

I have been referred to a urologist but it's the weekend so I have to wait til monday to make the appt. I am contemplating asking them to prescribe pain meds for me to have on hand just in case. Out of the 2 times I have been prescribed vicodin, or hydrocodone I only took 1/2 of one pill out of being scared of their affects on me, and/or my pregnancies. But I am very scared if I start passing any/all of them. I am making a list of questions to ask the urologist because I want to know why I am creating them so young and what my options are. If you know anything about them, please comment!

I found this picture along with a testimonial--this person says it's worse than child birth...and their stones were only 2-3 mm!