Hi, In 2014 A CT Scan Revealed A 5mm Left

Hi, in 2014 a CT scan revealed a 5mm left lower pole hypo dense lesion in my left kidney. I had no symptoms & then 7 months later, in April 2015, the same lesion was now 13mm. It's been about 18 months since initial scan, and now I'm suffering from abdominal pain & sometimes dark urine. . Is this something to be concerned about? Should I make an appointment with a specialist? If so, what type of Doctor?