Nov. 2013 my creatinine was 1.70 mg/dl. jan. 2014 it came down to 1.19 mg/dl. i exercise daily. what would be the reason of going ups and downs?

Varying GFR: This variation is unusual for a 33 yo. If not done, you need a urinalysis and a renal ultrasound. Possibilities include simple dehydration, exercise induced muscle breakdown and kidney injury, NSAID use, creatine use, a kidney disease that predisposes you to dehydration - associated renal insufficiency, kidney stone, or cystic kidney disease. Needs eval.