42 Year Male, Went For Physical, Everything Was Normal Except

42 year male, went for physical, everything was normal except gfr at 46 and creatinine of 1.6...doc retested and showed slight improvement of gfr to54 and creatinine of 1.5..doc also ran calcium and ionized, pth, phosp., magn., vita.d hydrox.25, bun, psa, all with in normal ranges, urinalysis was normal too! We both are confused, I'm an active person and do stay hydrated but do have minor back pains with burning sensations on sides of hips..what is going on?