I Have Had 2 MRIs, With And Without Contrast. 8/30/15

I have had 2 MRIs, with and without contrast. 8/30/15 and 1/13/16. In August I had 2 cysts on my left kidney, one being hyperdense, on the most recent they found that they have multiplied, not telling me how many there are now. I am very concerned about these findings being that I am only 30 years old. How concerned should I be?