Girls Only ? Quite Graphic!!! ?

Im a 13 year old girl. I started my period on May 8th 2011 and got it for the 2nd time June 5th. Since i started, i have had really heavy discharge when im coming on to my period and when im coming off of it. Its a stick whitish substance and it smells a bit like the flour from grated cheese (all i could think off!) Its very heavy ? any ways to stop this or anything ?