What Could White Clumpy Stuff In Vagina With Delayed Periods Mean?

I am late for my period by about a week. I took a pregnatcy test and it came back negative so I know that i'm not pregnant but the weird thing is that when my boyfriend fingers me there is white clumpy stuff on his fingers. I thought I had a yeasst infection but I don't have any other signs... I was wondering what the cause of all of this is?