Hello, i am 37, and have been having right flank pain recently. i got xrays taken a week ago, and was told today that they see "something" in the upper left quadrant and i need a ct scan. i'm wondering what the odds are that it's serious/cancer?

Cancer almost zero. Serious? time will tell.

I'll start by saying that without seeing the x-ray itself, and knowing what prompted the request for the CT, greatly limits one's ability to give an answer with any degree of certainty. That said; CT offers better resolution than a regular x-ray. It's often the case that CT is used to help clarify a finding on x-ray, and very often the finding is not significant. Your age makes cancer less likely