It is likely that the time you took creatine is too short for any serious renal damage. Laboratory tests might show if the creatinine level in the blood is increased. Creatinine is a break-down product of creatine in muscles.
The pain in the stomach and the kidneys are probably caused by infection. Therefore, the antibiotics might be very helpful. The presence of kidney stones that caused kidney inflammation can not be ruled out based on the provided data.
Kidney stones can be removed with surgery if they are too big. Flushing them by increasing the intake of fluids (water would be good enough) might be helpful if they are small enough. When using the latter method, the kidney stones might start damaging the walls of the ureters thus causing immense pain. So, the flushing might be done only after image examinations are done and if recommended by a medical professional.