Does stage three chronic kidney disease mean it will develop into stage four?

No. Absolutely not. In fact, if you do not have a real diagnosis, such as kidney damage from high blood pressure or diabetes, or glomerulonephritis or interstitial nephritis, be skeptical about the whole thing. At your age, creatinine levels can be up for a variety of reasons. When I was bodybuilding, mine ran 1.6-1.8 with perfectly good kidneys.