My Name is Siddharth Mehta, I am 17, and my question is in my routine blood tests, everything was perfect, just my serum creatinine was 0.66mg/dL, and the reference range of the lab was 0.8-1.2, but my doctor said low creatinine is nothing to worry about, is this true or should i consult a Nephrologist. Also I have severe muscle stiffness and my muscles are achy and weak, I consulted an orthopaedic, and my x-rays were fine, so he said there is no bone problem, and exercise would help reduce my muscle stiffness, should I visit a Rheumatologist, will he be able to help me out. And lastly can my muscle ache could be because of poor blood circulation, but my CBC and ESR are completely perfect, so should I also visit a hematologist.