I Have A Six Month Old Son Who Is Not

I have a six month old son who is not circumsized. I was told by doctors to pull back the foreskin a little at a time until the skin retracts all the way. This is my 3rd son and none of them are circumsized. I pulled back a little more than I meant to after my son's bath this evening and there is like a whitish coating on it. Any idea what it is and how to get rid of it?